Question about Ford F-150

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Fuel trim running rich how to correct it?

I have 2006 Ford F-150 4.2. The fuel trim running rich. Put a new fuel pump in it and change all fluids. The truck sat 4 years, it has 24,000 miles on it. Clean fuel injector. Need help. SHFT-1 both bank long term -30 give gas STFT goes -25 LTFT 0. Changed MAP sensor and coil, plug code P2196 / P2198 F-150 truck

Posted by melvin grasty on

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2 Answers

Jeff Armer

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  • Ford Master
  • 2,732 Answers

P2196 - O2 Sensor Signal Biased/Stuck Rich - Bank 1, Sensor 1 Description: A heated oxygen sensor (HO2S) indicating rich at the end of a test is trying to correct for an over-lean condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time. Possible Causes: See the possible causes for DTC P2195. Diagnostic Aids: Application Key On Engine Off Key On Engine Running Continuous Memory All GO to Pinpoint Test H .

Posted on Jan 15, 2022

  • 2 more comments 
  • Jeff Armer
    Jeff Armer Jan 15, 2022

    P2195 - O2 Sensor Signal Biased/Stuck Lean - Bank 1, Sensor 1
    Description: A heated oxygen sensor (HO2S) indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
    Possible Causes: Electrical:
    Short to VPWR in the harness or HO2S
    Water in the harness connector
    Open/shorted HO2S circuit
    Corrosion or incorrect harness connections
    Damaged HO2S
    Damaged powertrain control module (PCM)
    Fuel System:
    Excessive fuel pressure
    Leaking/contaminated fuel injectors
    Leaking fuel pressure regulator
    Low fuel pressure or running out of fuel
    Vapor recovery system
    Induction System:
    Air leaks after the mass air flow (MAF) sensor
    Vacuum leaks
    PCV system
    Improperly seated engine oil dipstick
    EGR System:
    Leaking gasket
    Stuck EGR valve
    Leaking diaphragm or EVR
    Base Engine:
    Oil overfill
    Camshaft timing
    Cylinder compression
    Exhaust leaks before or near the HO2S(s)

    Diagnostic Aids:
    Application Key On Engine Off Key On Engine Running Continuous Memory
    All — GO to Pinpoint Test H . GO to Pinpoint Test H .

  • Jeff Armer
    Jeff Armer Jan 15, 2022

    Conclusion: O2 Sensor measures oxygen through voltage. Air Fuel ratio sensor uses current to measure air to fuel ratio. AF sensor uses minimal current for its operation. This is the difference between Air fuel ratio sensor and O2 sensor other than the inner construction.

    This ford has O2 sensors
    https://www.tirereview.com/air-fuel-rati...

  • Jeff Armer
    Jeff Armer Jan 15, 2022

    https://www.youtube.com/watch?v=XfMuDkhn...

  • ADMIN Canada
    ADMIN Canada Jan 16, 2022

    Jeff, look. Is it only because I drive a Lexus. Different on domestic cars?

    WHAT IS THE AIR FUEL RATIO SENSOR
    Cars have had oxygen sensors since the 1980’s, but in the early 2000’s, more accurate sensors were developed leading to the air fuel ratio sensors (A/F). The A/F sensor takes note of the oxygen content of the car’s exhaust in a more expansive, effective way. Even though it looks similar to the oxygen sensor, it has more visible wires. The A/F can sense a much larger and leaner span of fuel mixtures. Due to this ability, it is also called a wideband or broadband sensor.

    The air fuel ratio sensor is typically in the exhaust manifold or in the front exhaust pipe. It measures the oxygen in the exhaust and sends that information to the ECU. The ECU, based on the air-to-fuel ratio, adjusts the blend to keep it at the prime level. This level is generally 14.7:1. It is important that the A/F sensor remain in good condition in order to keep your car running at this optimum level.

    WHAT IS THE OXYGEN SENSOR?
    The oxygen sensor (O2) is an important part of your car’s emissions system and has been since the initial use of ECUs. The O2 sensors were created to keep tabs on how much oxygen is in your vehicle’s exhaust stream checking for efficiency confirming that the catalytic converter is functioning properly.

    The sensor notes whether the air/fuel mixture is too lean or too rich. That knowledge is sent back to the ECU which adjusts the metering and timing of the fuel to make sure your car is running on the proper mixture. These readings change as you go up hills, accelerate, have just begun driving, change engine temperature and other elements. Since your car has two sensors checking the exhaust, the O2 sensor will be on the other side of the catalytic converter from the A/F.

    WHY IS IT NECESSARY TO HAVE BOTH SENSORS?
    Newer vehicles, like your Lexus or luxury car, have both sensors. One is “downstream” of the converter and the other is “upstream.” The reasoning behind having both sensors is to better calibrate the information the ECU receives. In short, two readings are better than one. These readings will give the information necessary to make sure your car is working at the top performance level which will affect a number of things including quality of the ride and your gas mileage. Cars and trucks with dual exhaust have two sensors on each exhaust pipe.

    If you have any questions regarding the air fuel ratio sensor or the oxygen sensor in your Lexus, please contact Earnhardt Lexus or our service department to learn more. Remember that it is important to pay attention to the sensor warning lights to make sure your car is evaluated thus keeping it running smoothly and at the level you expect from a luxury brand.

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ADMIN Canada

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  • Ford Master
  • 42,942 Answers

Question edited for clarity.
Question moved to Ford F-150

Your codes are telling you that the Fuel Air Sensors (mistakenly called O2 sensors) need replacing. The sensors are showing 'running rich', so the ECM is substracting fuel, so the vehicle is actually running lean, not enough fuel. You will burn valve seats, piston crowns and plugs if you don't fix! Letting the truck sit has ruined the sensors. Amazingly low mileage. DON'T buy cheap sensors, buy Denso or Ford OEM.

P2196 - Meaning, Causes, Symptoms, & Fixes - FIXD

https://www.fixdapp.com > blog > p2196-code
Oct 15, 2018 - Code P2196 is a result of the pre-catalytic converter oxygen sensor detecting a rich air to fuel ratio of the exhaust on bank 1.

2198 is bank 2

Posted on Jan 15, 2022

Testimonial: "I think you for your answer I was thinking it was the o2 but didn't want both was bad at the same time . will replace in the days to come after I get my heart surgery done in few days .and Thank you very much"

  • 3 more comments 
  • Jeff Armer
    Jeff Armer Jan 15, 2022

    Fuel Air Sensors ??? it is a O2 sensor , it sense oxygen in the exhaust not fuel / Right out of ford repair manual .
    P2198 - O2 Sensor Signal Biased/Stuck Rich - Bank 2, Sensor 1
    Description: See the description for DTC P2196.
    Possible Causes: See the possible causes for DTC P2195.
    Diagnostic Aids:
    Application Key On Engine Off Key On Engine Running Continuous Memory
    All GO to Pinpoint Test H .

    2006 PCED On Board Diagnostics SECTION 5: Pinpoint Tests
    Procedure revision date: 06/26/2005

    --------------------------------------------------------------------------------
    H: Fuel Control H: Introduction

    --------------------------------------------------------------------------------

    H1 CHECK FOR DTCS
    Are DTCs P0171, P0172, P0174, P0175, P2195, P2196, P2197, P2198, P2270, P2271, P2272, P2273, P2274, or P2275 present?
    Yes No
    For DTCs P2270, P2271, P2272, P2273, P2274 or P2275, GO to H26 .

    For DTCs P0171, P0174, P2195 or P2197, GO to H2 .

    For DTCs P0172, P0175, P2196 or P2198, GO to H8 . For all others, GO to Section 4, Diagnostic Trouble Code (DTC) Charts and Descriptions .

    H2 DTCS P0171, P0174, P2195 OR P2197: LEAN SYSTEM DTCS
    Note: Do not clear the DTCs or reset the keep alive memory (KAM).

    Access the PCM and record the ECT PID from the freeze frame data. The freeze frame data is used to recreate the concern.
    Retrieve and record the self-test DTCs.
    Are any DTCs present other than the following: P0171, P0174, P2195 or P2197?
    Yes No
    DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to Section 4, Diagnostic Trouble Code (DTC) Charts and Descriptions . GO to H3 .

    H3 CARRY OUT A VISUAL INSPECTION ON THE INTAKE AIR SYSTEM AND ALL VACUUM HOSES
    Key in OFF position.
    Check the intake air system for leaks, obstructions, and damage.
    Inspect the entire length of all the vacuum hoses for:
    proper connections
    damage or cracks
    damaged or cracked vacuum tees
    Verify the integrity of the positive crankcase ventilation (PCV) system.
    Verify the proper PCV valve part number.
    Is a concern present?
    Yes No
    GO to H6 . GO to H4 .

    H4 CHECK FOR THE PRESENCE OF A VACUUM LEAK
    Note: Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle.

    Note: The barometric pressure (BARO) PID is not a recommended PID to monitor when diagnosing a vacuum leak. Barometric pressure is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow.

    Note: When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT2 equals +24% and SHRTFT2 equals -3% the total fuel correction for bank 2 equals +21%.

    Note: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).

    Key ON, engine running.
    Access the PCM and monitor the ECT, CHT and IAT PIDs.
    Access the PCM and monitor the LONGFT1, SHRTFT1, LONGFT2 and SHRTFT2 PIDs.
    Allow the engine to stabilize at the temperature necessary to recreate the concern.
    Mathematically add and record the LONGFT PID value to the SHRTFT PID value for each bank, for a total fuel correction at idle.
    Increase the engine speed to 2,500 RPM for 10 seconds.
    Record the LONGFT1, SHRTFT1, LONGFT2, and SHRTFT2 PID values.
    Mathematically add and record the LONGFT PID value to the SHRTFT PID value for each bank, for a total fuel correction at 2,500 RPM.
    Is the total fuel correction value difference, between idle and 2,500 RPM, less than 15 percent?
    Yes No
    No vacuum leak is present.

    For DTCs P0171, P0174, P2195, or P2197 with a secondary air injection (AIR) system, GO to H7 .

    For DTCs P0171 or P0174 without a secondary air injection (AIR) system, GO to H16 .

    For DTCs P2195 or P2197 without a secondary air injection (AIR) system, GO to H10 . GO to H5 .

    H5 LOCATE THE VACUUM LEAK
    CAUTION: Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose.

    Note: Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Carry out a visual inspection as necessary.

    Note: When monitoring for a decrease in the SHRTFT PIDs in the following steps, if SHRTFT1 equals +15% and the hose is restricted, SHRTFT1 decreases to -7%. The total decrease in the SHRTFT PIDs equals 22%.

    Locate the vacuum tees for the intake air and PCV systems.
    Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
    Restrict the vacuum lines one at a time for 30 seconds. If a vacuum leak is present, the SHRTFT PID values decrease as the hose is restricted.
    Is the decrease in the SHRTFT PIDs greater than 15 percent when one of the vacuum hoses is restricted?
    Yes No
    GO to H6 . INSPECT the intake air system for a vacuum leak in the intake manifold or intake gaskets. REPAIR as necessary.

    For repair verification, GO to H6 .

    H6 VACUUM LEAK REPAIR VERIFICATION
    Note: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).

    Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
    Allow the engine to stabilize at the temperature necessary to recreate the concern.
    Record the SHRTFT1 and SHRTFT2 PID values.
    Key in OFF position.
    Repair the vacuum leak.
    Key ON, engine running.
    Allow the engine to stabilize at the temperature necessary to recreate the concern.
    Access the PCM and monitor the SHRTFT1 and SHRTFT2 PIDs.
    Compare the recorded SHRTFT PID values, prior to the vacuum leak repair, to the current SHRTFT PID values.
    Is the decrease in the SHRTFT PIDs greater than 15 percent?
    Yes No
    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test. A vacuum leak is still present.

    GO to H5 .

    H7 CHECK FOR SECONDARY AIR LEAKS
    Note: An HO2S always lean condition can be caused by:

    leaks in the hoses from the secondary air injection pump to the engine.
    secondary air diverted upstream of the HO2S.

    Disconnect the secondary air injection hose(s) from the engine and the plug side of the secondary air injection system.
    Key ON, engine running.
    Carry out the self-test.
    Are DTCs P0171, P0174, P2195 or P2197 present?
    Yes No
    For DTCs P0171 or P0174, GO to H16 .

    For DTCs P2195 or P2197, GO to H10 . GO to HM18 .

    H8 DTCS P0172, P0175, P2196 OR P2198: RICH SYSTEM DTCS
    Note: Do not clear the DTCs or reset the keep alive memory (KAM).

    Access the PCM and record the freeze frame data.
    Retrieve and record the self-test DTCs.
    Are any DTCs present other than the following: P0172, P0175, P2196 or P2198?
    Yes No
    DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO to Section 4, Diagnostic Trouble Code (DTC) Charts and Descriptions . GO to H9 .

    H9 INSPECT THE ENTIRE INTAKE AIR SYSTEM FOR DEBRIS, BLOCKAGE OR OTHER DAMAGE
    Check the intake air system for obstructions, restrictions, and damage.
    Check the throttle plate for obstructions or sludge.
    Check the air filter element and housing for blockage.
    Is a concern present?
    Yes No
    REPAIR as necessary.

    CLEAR the DTCs. REPEAT the self-test. For DTCs P0172 or P0175, GO to H16 .

    For DTCs P2196 or P2198, GO to H14 .

    H10 CHECK THE HO2S AND SIGRTN CIRCUIT(S) FOR AN OPEN IN THE HARNESS
    Key in OFF position.
    Disconnect the HO2S related to the current DTC.
    PCM connector disconnected.
    Measure the resistance between:

    ( + ) HO2S Connector, Harness Side ( - ) PCM Connector, Harness Side
    HO2S Signal HO2S Signal
    SIGRTN SIGRTN


    Are the resistances less than 5 ohms?
    Yes No
    GO to H11 . REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

    H11 CHECK THE HO2S CIRCUIT FOR A SHORT TO SIGRTN IN THE HARNESS
    Measure the resistance between:

    ( + ) HO2S Connector, Harness Side ( - ) HO2S Connector, Harness Side
    HO2S Signal SIGRTN


    Is the resistance greater than 10K ohms?
    Yes No
    GO to H12 . REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

    H12 CHECK THE HO2S CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS
    Measure the resistance between:

    ( + ) HO2S Connector, Harness Side ( - )
    HO2S Signal Ground


    Is the resistance greater than 10K ohms?
    Yes No
    GO to H13 . REPAIR the short circuit to GND. CLEAR the DTCs. REPEAT the self-test.

    H13 HO2S CIRCUIT TEST (WITH LEAN DTCS)
    PCM connector connected.
    Connect a 5 amp fused jumper wire between the following:

    Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
    HO2S Signal VPWR


    Key ON, engine OFF.
    Access the PCM and monitor the HO2S Signal PID.
    Is the voltage greater than 1.3 V?
    Yes No
    GO to H16 . GO to H36 .

    H14 HO2S CIRCUIT TEST (WITH RICH DTCS)
    Disconnect the HO2S related to the current DTC.
    Key ON, engine OFF.
    Access the PCM and monitor the HO2S Signal PID.
    Is the voltage less than 0.2 V?
    Yes No
    GO to H16 . GO to H15 .

    H15 CHECK THE HO2S CIRCUIT FOR A SHORT TO THE VPWR OR HEATER IN THE HARNESS
    Key in OFF position.
    PCM connector disconnected.
    Measure the resistance between:

    ( + ) PCM Connector, Harness Side ( - ) PCM Connector, Harness Side
    HO2S Signal HO2S Heater
    HO2S Signal VPWR


    Are the resistances greater than 10K ohms?
    Yes No
    GO to H36 . REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

    H16 CHECK THE FUEL PRESSURE
    WARNING: WHEN CHECKING THE FUEL SYSTEM REMEMBER THAT THE FUEL SYSTEM MAY STILL BE PRESSURIZED WHEN THE ENGINE IS SWITCHED OFF. ALWAYS FOLLOW THE INSTRUCTIONS RELATED TO FUEL SYSTEM PRESSURE RELIEF. ALL FUEL HANDLING SAFETY PRECAUTIONS MUST BE OBSERVED. FAILURE TO FOLLOW THESE INSTRUCTIONS MAY RESULT IN PERSONAL INJURY.

    Note: For vehicle specific fuel pressure ranges, refer to the Fuel System Specification Chart in pinpoint test HC.

    Remove the jumper wire(s).
    HO2S connector connected.
    Relieve the fuel pressure. Refer to the Workshop Manual Section 310-00, Fuel System for the Fuel System Pressure Release procedure.
    Mechanical fuel pressure gauge connected.
    Pressurize the fuel system. Refer to the Workshop Manual Section 310-00, Fuel System for the Fuel System Pressure Release procedure to pressurize the fuel system.
    Key ON, engine running.
    Allow the fuel pressure to stabilize.
    Key in OFF position.
    Key ON, engine running.
    Access the PCM and control the FP PID.
    Run the fuel pump to obtain maximum fuel pressure.
    Is the fuel pressure within range for the vehicle being diagnosed?
    Yes No
    GO to H17 . GO to Pinpoint Test HC .

    H17 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - FAST LEAKDOWN
    Note: When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize.

    Note: During output state control, the fuel pump stays commanded on for only about 5 seconds.

    Key in OFF position.
    Key ON, engine OFF.
    Access the PCM and control the FP PID.
    Run the fuel pump to obtain maximum fuel pressure.
    Command the fuel pump off.
    Allow the fuel pressure to stabilize.
    Record the stabilized reading.
    Monitor the fuel pressure for 10 seconds.
    Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 10 seconds?
    Yes No
    GO to H19 . GO to H18 .

    H18 CHECK FOR AN EXTERNAL FUEL LEAK
    Inspect the fuel tank, lines, and filler pipe for a fuel leak.
    Is a concern present?
    Yes No
    REPAIR as necessary.

    REFER to the fuel system WARNING information at the beginning of Pinpoint Test HC. GO to Pinpoint Test HC .

    CLEAR the DTCs. REPEAT the self-test. GO to H20 .

    H19 CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - SLOW LEAKDOWN
    Continue to monitor the fuel pressure for 1 minute.
    Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading (MRFS) or greater than 275 kPa (40 psi) (ERFS) after 1 minute?
    Yes No
    GO to H20 . GO to HC7 .

    H20 FLOW TEST
    Key in OFF position.
    PCM connector connected.
    Flow test the injector using the fuel injector tester.
    Is the flow rate for each injector within specification?
    Yes No
    For DTCs P0171, P0172, P0174 or P0175, GO to DC28 .

    For DTCs P2195 or P2197, GO to H21 .

    For DTCs P2196 or P2198, GO to H22 . INSTALL a new fuel injector. REFER to the Workshop Manual Section 303-04, Fuel Charging and Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test.

    H21 CHECK THE HO2S OUTPUT VOLTAGE
    HO2S connector disconnected.
    Visually inspect the HO2S circuit for exposed wiring, contamination, corrosion and correct assembly. Repair as necessary.
    Measure the voltage between:

    ( + ) HO2S Connector, Component Side ( - ) HO2S Connector, Component Side
    HO2S Signal SIGRTN


    Increase the engine speed to 2,000 RPM for 3 minutes.
    Carry out the KOER self-test.
    Monitor the signal voltage during the self-test.
    Is the voltage greater than 0.5 volt at any time during the self-test?
    Yes No
    GO to H24 . INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test.

    H22 ATTEMPT TO RETRIEVE DTC P2195 OR P2197
    HO2S connector disconnected.
    Connect a 5 amp fused jumper wire between the following:

    Point A HO2S Connector, Harness Side Point B Vehicle Battery
    HO2S Signal Negative terminal


    Carry out the KOER self-test.
    Are DTCs P2195 or P2197 present?
    Yes No
    GO to H23 . GO to H36 .

    H23 HO2S VOLTAGE CHECK
    Key in OFF position.
    Remove the jumper wire(s).
    HO2S connector disconnected.
    Key ON, engine running.
    Increase the engine speed to 2,000 RPM for 30 seconds.
    Measure the voltage between:

    ( + ) HO2S Connector, Component Side ( - ) HO2S Connector, Component Side
    HO2S Signal SIGRTN


    Carry out the KOER self-test.
    Monitor the signal voltage during the self-test.
    Is the voltage less than 0.4 volt at any time during the self-test?
    Yes No
    GO to H24 . INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test.

    H24 CARRY OUT A THOROUGH WIGGLE TEST ON THE HO2S HARNESS
    Key in OFF position.
    HO2S connector connected.
    Key ON, engine running.
    Engine at normal operating temperature.
    Access the PCM and monitor the HO2S Signal PID.
    Wiggle, shake, and bend small sections of the wiring harness while working from the sensor to the PCM.
    While monitoring the HO2S PID, does the HO2S stop switching?
    Yes No
    ISOLATE the concern and REPAIR as necessary.

    CLEAR the DTCs. REPEAT the self-test. GO to H25 .

    H25 TEST DRIVE THE VEHICLE WHILE MONITORING THE HO2S PID FOR SWITCHING
    Access the PCM and monitor the HO2S Signal, OL and LOOP PIDs.
    Start the engine and let idle until the vehicle goes into the closed loop fuel condition.
    Drive the vehicle in a manner consistent with the freeze frame data in an attempt to simulate the original concern.
    Does the HO2S PID switch?
    Yes No
    GO to DC28 . INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test.

    H26 DTCS P2270, P2272, P2271, P2273, P2274 OR P2275: HO2S LACK OF SWITCHES STUCK LEAN OR RICH
    Note: Address all continuous memory ignition and misfire DTCs before any KOER HO2S DTCs.

    Key in OFF position.
    Visually inspect for:
    pinched, shorted, and corroded wiring and pins
    oil or water contamination
    crossed sensor wires
    contaminated or damaged sensor
    Is a concern present?
    Yes No
    REPAIR as necessary.

    CLEAR the DTCs. REPEAT the self-test. For KOER DTCs P2270, P2271, P2272, P2273, P2274 or P2275, GO to H28 .

    For continuous memory DTCs P2270, P2271, P2272, P2273, P2274 or P2275, GO to H27 .

    H27 CHECK FOR KOER DTCS
    Key ON, engine OFF.
    Clear the DTCs.
    Key ON, engine running.
    Run the engine at approximately 2,000 RPM. Maintain the engine speed for 3 minutes.
    Retrieve the continuous memory DTCs.
    Are DTCs P2270, P2271, P2272, P2273, P2274 or P2275 present?
    Yes No
    GO to H28 . Unable to duplicate or identify the concern at this time.

    GO to Pinpoint Test Z .

    H28 CHECK THE HO2S SIGNAL LEVEL TOO HIGH
    Note: Fuel calculations can be affected by unmetered air leaks.

    Key in OFF position.
    Carefully inspect the following areas for potential air leaks:
    hoses connecting to the mass air flow (MAF) sensor assembly
    hoses connecting to the throttle body
    intake manifold gasket leaks
    PCV system
    the vacuum lines are disconnected
    improperly seated engine oil dipstick, tube or oil fill cap
    exhaust leaks at flanges and gaskets
    With the vehicle in NEUTRAL, position it on a hoist. Refer to the Workshop Manual Section 100-02, Jacking and Lifting for the locations of the lifting points.
    Visually inspect for:
    exhaust leaks at flanges and gaskets
    HO2S not tightened to specification
    physical exhaust system concerns
    aftermarket exhaust
    punctures or cracks in the catalyst
    Is a concern present?
    Yes No
    REPAIR as necessary.

    CLEAR the DTCs. REPEAT the self-test. GO to H29 .

    H29 CHECK FOR SHORTS BETWEEN CIRCUITS IN THE HO2S HARNESS
    PCM connector disconnected.
    Disconnect the HO2S harness connector.
    Measure the resistance between:

    ( + ) PCM Connector, Harness Side ( - ) Vehicle Battery
    HO2S Signal Negative terminal


    Measure the resistance between:

    ( + ) PCM Connector, Harness Side ( - ) PCM Connector, Harness Side
    HO2S Signal SIGRTN
    HO2S Signal VPWR
    HO2S Signal HO2S Heater


    Are the resistances greater than 10K ohms?
    Yes No
    GO to H30 . REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

    H30 CHECK THE HO2S CIRCUIT FOR AN OPEN IN THE HARNESS
    Measure the resistance between:

    ( + ) PCM Connector, Harness Side ( - ) HO2S Connector, Harness Side
    HO2S Heater HO2S Heater
    VPWR VPWR
    HO2S Signal HO2S Signal
    SIGRTN SIGRTN


    Are the resistances less than 5 ohms?
    Yes No
    GO to H31 . REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

    H31 CHECK THE HO2S CIRCUIT VOLTAGE
    PCM connector connected.
    HO2S connector connected.
    Key ON, engine running.
    Access the PCM and monitor the HO2S Signal PID.
    Is the voltage greater than 1.5 V?
    Yes No
    For partial zero emission vehicle (PZEV), GO to H34 .

    For all others, GO to H33 . GO to H32 .

    H32 CHECK THE HO2S CIRCUIT VOLTAGE
    Key in OFF position.
    PCM connector connected.
    HO2S connector disconnected.
    Connect a 5 amp fused jumper wire between the following:

    Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
    HO2S Signal VPWR


    Key ON, engine OFF.
    Access the PCM and monitor the HO2S Signal PID.
    Is the voltage greater than 1.5 V?
    Yes No
    INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test. GO to H36 .

    H33 CHECK FOR OVER VOLTAGE IN THE PCM
    Key in OFF position.
    HO2S connector disconnected.
    Key ON, engine OFF.
    Measure the voltage between:

    ( + ) HO2S Connector, Harness Side ( - ) Vehicle Battery
    SIGRTN Negative terminal
    HO2S Signal Negative terminal


    Are the voltages less than 1.5 V?
    Yes No
    INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test. GO to H36 .

    H34 CHECK THE HO2S CIRCUIT FOR A SHORT TO VPWR IN THE HARNESS
    Key in OFF position.
    PCM connector disconnected.
    HO2S connector disconnected.
    Measure the resistance between:

    ( + ) PCM Connector, Harness Side ( - ) HO2S Connector, Harness Side
    HO2S Signal VPWR


    Is the resistance greater than 10K ohms?
    Yes No
    GO to H35 . REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.

    H35 CHECK THE HO2S CIRCUIT VOLTAGE
    PCM connector connected.
    HO2S connector disconnected.
    Connect a 5 amp fused jumper wire between the following:

    Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
    HO2S Signal VPWR


    Key ON, engine running.
    Access the PCM and monitor the HO2S Signal PID.
    Is the voltage greater than 1.5 V?
    Yes No
    INSTALL a new HO2S. REFER to the Workshop Manual Section 303-14, Electronic Engine Controls.

    RESET the keep alive memory (KAM). REFER to Section 2, Resetting The Keep Alive Memory (KAM) .

    REPEAT the self-test. GO to H36 .

    H36 CHECK FOR CORRECT PCM OPERATION
    Disconnect all the PCM connectors.
    Visually inspect for:
    pushed out pins
    corrosion
    Connect all the PCM connectors and make sure they seat correctly.
    Carry out the PCM self-test and verify the concern is still present.
    Is the concern still present?
    Yes No
    INSTALL a new PCM. REFER to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.




    --------------------------------------------------------------------------------

  • ADMIN Canada
    ADMIN Canada Jan 15, 2022

    Hi Jeff
    My garage tech told me, and confirmed by reading that the sensor before the catalytic converter adjusts the fuel and air mixture to create the correct amount of fuel to combust correctly. The sensor after the catalytic converter senses whether the Cat is doing its job correctly and makes further adjustments. When I bought my Bank 1 Sensor 1, Denso sold it as a Fuel Air Sensor, Sensor 2 was sold as Heated Oxygen Sensor. Not correct?

    This graphic calls is an A/F Sensor on my vehicle (not the highlighted ones, the one above).
    https://f01.justanswer.com/ebrock63/78e6...

    ..

  • ADMIN Canada
    ADMIN Canada Jan 16, 2022

    Jeff, it appears you agree with me. Puzzled??

    O2 Sensor measures oxygen through voltage. Air Fuel ratio sensor uses current to measure air to fuel ratio. AF sensor uses minimal current for its operation. This is the difference between Air fuel ratio sensor and O2 sensor other than the inner construction.

  • ADMIN Canada
    ADMIN Canada Jan 16, 2022

    Jeff. look

    Denso 234-9023 Air Fuel Ratio Sensor - Amazon.cahttps://www.amazon.ca › Denso-234-9023-Fuel-Ratio-S...
    Denso Air and Fuel Ratio sensor is designed to detect the amount of the exhaust gas air and fuel ratio. It is constructed from durable material that is ...
    Air Fuel ratio sensor from www.amazon.ca

  • ADMIN Canada
    ADMIN Canada Jan 16, 2022

    WHAT IS THE AIR FUEL RATIO SENSOR
    Cars have had oxygen sensors since the 1980’s, but in the early 2000’s, more accurate sensors were developed leading to the air fuel ratio sensors (A/F). The A/F sensor takes note of the oxygen content of the car’s exhaust in a more expansive, effective way. Even though it looks similar to the oxygen sensor, it has more visible wires. The A/F can sense a much larger and leaner span of fuel mixtures. Due to this ability, it is also called a wideband or broadband sensor.

    The air fuel ratio sensor is typically in the exhaust manifold or in the front exhaust pipe. It measures the oxygen in the exhaust and sends that information to the ECU. The ECU, based on the air-to-fuel ratio, adjusts the blend to keep it at the prime level. This level is generally 14.7:1. It is important that the A/F sensor remain in good condition in order to keep your car running at this optimum level.

    WHAT IS THE OXYGEN SENSOR?
    The oxygen sensor (O2) is an important part of your car’s emissions system and has been since the initial use of ECUs. The O2 sensors were created to keep tabs on how much oxygen is in your vehicle’s exhaust stream checking for efficiency confirming that the catalytic converter is functioning properly.

    The sensor notes whether the air/fuel mixture is too lean or too rich. That knowledge is sent back to the ECU which adjusts the metering and timing of the fuel to make sure your car is running on the proper mixture. These readings change as you go up hills, accelerate, have just begun driving, change engine temperature and other elements. Since your car has two sensors checking the exhaust, the O2 sensor will be on the other side of the catalytic converter from the A/F.

    WHY IS IT NECESSARY TO HAVE BOTH SENSORS?
    Newer vehicles, like your Lexus or luxury car, have both sensors. One is “downstream” of the converter and the other is “upstream.” The reasoning behind having both sensors is to better calibrate the information the ECU receives. In short, two readings are better than one. These readings will give the information necessary to make sure your car is working at the top performance level which will affect a number of things including quality of the ride and your gas mileage. Cars and trucks with dual exhaust have two sensors on each exhaust pipe.

    If you have any questions regarding the air fuel ratio sensor or the oxygen sensor in your Lexus, please contact Earnhardt Lexus or our service department to learn more. Remember that it is important to pay attention to the sensor warning lights to make sure your car is evaluated thus keeping it running smoothly and at the level you expect from a luxury brand.

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Related Questions:

1helpful
1answer

Does the 94 lincoln tc exec come with the pats system

if its been sat for years the fuel filter has probably deteriorated, and its now in the fuel lines. there is a number of parts that need changing before you start an engine that has not been run in a long time. fuel drained, fuel filter changed, oil and filter changed. fuel goes off after a year or 2. oil can turn to sludge in the sump. and block the oil pump. this can also affect the oil pressure sensor.
0helpful
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Truck is running rough. Changed intake gasket, brake booster, and put in new spark plugs. Truck runs good for a few miles then it runs rough again. What could this be?

Do you have a check engine light on ? Is it cold when it runs good an then not when it warms up ? You need to have a diagnostic scan tool hooked up , check engine sensor data parameters .Have a pro diagnose it before replacing parts .ECT - engine coolant temp . sensor , mass air flow sensor , O2 sensors , also check fuel trims , if you know what those are . Fuel trims are a good diagnostic tool , is the PCM adding fuel for lean condition ., low fuel pressure ,plugged fuel filter , worn fuel pump etc... Or is the PCM subtracting fuel , leaking fuel injectors , bad fuel pressure regulator . What make , model an year vehicle ?
1helpful
1answer

Two codes 1 po172 bank 1 running rich / 2 po300 missfire where to start ?

You could have leaking fuel injectors an fouled spark plugs causing the misfire ! I would pull the spark plugs out an see if wet with fuel . Could also have a leaking fuel pressure regulator ! How To Fix P0300 random misfire codes in your car

O2 Sensor Signal Fixed Rich http://youtu.be/H6lY42u19VM
The front oxygen sensor sends signals on exhaust gas oxygen content to the PCM to control a 14.7:1 air/fuel ratio under normal driving conditions. The PCM can make fuel corrections from a nominal 128 (0% correction) short/long term fuel trim value to a maximum window of 101-147 (-21 to +15 percent). If the PCM determines a rich condition exists, 02 voltage above 450 mV, it will decrease injector pulse width, reducing fuel, to maintain a 14.7:1 air/fuel ratio. The short term fuel trim value will be between 101-128 indicating a rich condition. If the PCM determines a lean condition exists, 02 voltage below 450 mV, it will increase injector pulse width, adding fuel, maintaining a correct air/fuel mixture. The short term fuel trim value will be between 128-147 indicating a lean condition. When certain conditions have been met to begin learning fuel control (ECT, closed loop, etc.) the PCM will use the short term fuel trim cell to update 1 of the 4 long term cells (idle, decel, cruise, accel) being used. During every drive cycle, or trip, the PCM will use and update the idle and cruise long term cells and will keep track of how long the control system is operating in these cells. After approximately 2 minutes of being in each of these cells, the fuel control system will enable EVAP purge and the purge long term cells will be used. Refer to EVAP Canister Purge for information on purge long term fuel cells. If the average of the idle and cruise fuel cells is 147 and the short term fuel trim cell is currently over 128, a lean fuel system DTC will set. This test is performed before the purge cells are used.
http://youtu.be/QDNrFcARMd0


0helpful
2answers

96 acura tl 2.5 liter,short term fuel trim at negative 20 percent

Do a cylinder leak down test,for bad valves on #3
or head gasket,misfires for a reason

(Cam Worn ?)

Have to get rid of any misfires

If your taking out 20% your correcting for a rich condition,maybe

Some injector issues,old,need to be sent away for cleaning & flow
testing or replaced?

Drive it for 30 miles & add short & long term & see what you get

Exhaust Converter any good ?
0helpful
1answer

1998 mustang cobra runs good cold but as soon as it hits running temp it runs a little rough with loss of power

Check your fuel pressure and your fuel filter . Also check your pids.
which the most important one is your short term fuel trim while it's running ,it will be either rich or lean . I know it sounds silly but when the numbers are positive it's lean and when there negative it's running rich.
0helpful
1answer

Engine light on and misfiring and want to fix this and get it running smooth

The cylinder misfires cause lean or rich
fuel trim

A constant lean on fuel trim, is a rich condition
driven lean by pcm to correct

If two cylinder are affected & are together or maybe
not ,then smoke the intake for vacuum leaks

A leaking injector is obviously a rich senerio

Converter only works with the O2 Sesnors to report
back the rich or lean to pcm

You need to get rid of the misfires before any fuel control
returns to normal
1helpful
1answer

Car runs fine at idle when givin gas it breaks up bad and the cat. converter turns red replaced the cat. put in new plugs and changed cam sensors car still does the same thing but gives no code

Catalytic Converters run very hot only when too much fuel used.

Find the cause of overly rich fuel condition. Over fueling will also cause running problems you are experiencing.

You need to check the Short Term Fuel Trim with a scanner. If higher than -12% you have an injector staying open too long or too high fuel pressure.

This is the corrective strategy the ECU uses to trim the fuel to lambda. ie: 14 to 1.C/0%

If it is too lean, it would read + instead of - .
0helpful
1answer

I have a scion tc 05 with this code p171 . what does it mean?

DTC P0171 is set when fuel trim is driven rich beyond a certain value. Possible causes are:
1. Exhaust system leak.
2. Improper fuel pressure.
3. Fuel injector restricted.
4. Defective heated oxygen sensor No. 1.
5. Defective Manifold Absolute Pressure (MAP) sensor.
6. Defective Engine Coolant Temperature (ECT) sensor.
When the air fuel ratio feedback is stable after the engine is at operating temperature and the fuel trim has reached its limit of correction to the rich side. (2 trip logic).
Feedback from the HO 2 sensor influences short-term fuel trim and short-term fuel trim influences long trim fuel trim. Short-term values are temporary and not stored when the ignition key is turned off. Long-term values are stored in memory because they are part of the basic injection duration. Long term values affect injection duration in closed and open loop because they are used to calculate basic injection duration. It is important to remember that the actual fuel trim will be the opposite of the DTC. A system too lean, DTC P0171 will mean the ECM is making a + or rich correction.
read (and let me know)above data and Freeze Frame by using (example, generic) Scan Tool on # mode 2, etc.
Slowly accelerate the engine in the increments shown and record voltage,
grams/sec of MAF and SFT, LFT, Injection Pulse, Fuel Pressure, etc.
HTH,
Vehicle have MAF Sensor?
0helpful
2answers

Function of oxygen sensor?

It measures the oxygen in the exhaust system, for instance, if the fuel is to rich it sends values to the computer and the computer will adjust the fuel and timing to bring it back into perimeters
14helpful
2answers

What is a STFT B1(%) -1.56. WHAT DOES THAT MEAN?

Here is some general information to get you started...
(I am quoting directly from several PDF sources, Googled).

STFT B1 = Short Term Fuel Trim Bank 1. This is the fuel correction percentage being used by the closed loop fuel strategy for Bank 1 (if a V style engine or for all cylinders if an inline engine). If the fuel system is in open loop, this number will be reported as 0%

Fuel trim refers to the feedback compensation value compared against the basic injection time. Fuel trim includes short–term fuel trim and long–term fuel trim.

Short–term fuel trim is the short–term fuel compensation used to maintain the air–fuel ratio at its ideal theoretical value. The signal from the heated oxygen sensor indicates whether the air–fuel ratio is RICH or LEAN compared to the ideal theoretical value, triggering a reduction in fuel volume if the air–fuel ratio is rich, and an increase in fuel volume if it is lean.

Long–term fuel trim is overall fuel compensation carried out long–term to compensate for continual deviation of the short–term fuel trim form the central value due to individual engine differences, wear over time and changes in the usage environment.

If both the short–term fuel trim and long–term fuel trim are LEAN or RICH beyond a certain value, it is detected as a malfunction and the check engine warning (CHK ENG) lights up.

If the total of the short–term fuel trim value and long–term fuel trim value is within ± 25 %, the system is functioning normally.
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