Question about 2006 Mercedes-Benz ML-Class

1 Answer

Ml500 codes 172 and 175

Is there a common issue with this vehicle that would result in these engine codes? They indicate bank 1 and 2 running rich. Is there anything I can try before taking it to a mechanic? Thanks.

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Top Expert:

    An expert who has finished #1 on the weekly Top 10 Fixya Experts Leaderboard.

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

  • Master
  • 1,007 Answers

Try cleaning the EGR system, valves and pipes.

Posted on Nov 01, 2012

2 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

ZJLimited
  • 17970 Answers

SOURCE: 2003 c230 kompressor

P0172 - System Too Rich (Bank 1)
Basically this means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0175, and in fact your vehicle may show both codes at the same time.

Symptoms: You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire. This is the next code explained.

Causes: A code P0172 may mean that one or more of the following has happened:
* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak.
* There could be a fuel pressure or delivery problem

Possible solutions include:
* Inspect all vacuum and PCV hoses, replace if necessary
* Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
* Inspect fuel lines for cracks, leaks, or pinches
* Check the fuel pressure at the fuel rail
* Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
* Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)


P0301 - Cylinder 1 One Misfire Detected
A P0301 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #1.

Symptoms may include:
* the engine may be harder to start
* the engine may stumble / stumble, and/or hesitate
* other symptoms may also be present

Causes: A code P0301 may mean that one or more of the following has happened:
* Faulty spark plug or wire
* Faulty coil (pack)
* Faulty oxygen sensor(s)
* Faulty fuel injector
* Burned exhaust valve
* Faulty catalytic converter(s)
* Running out of fuel
* Poor compression
* Defective computer

Possible Solutions:
* If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
* If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.


Keep in mind that the "misfiring" are not only for bad O2 sensors, check the other componentes that I tell you before.

Keep us updated.

Posted on Jan 19, 2011

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

2 Answers

What does code p1131 mean on a 2001 ford taurus


P1131 Ford
P1131 Ford - Lack of Upstream Heated Oxygen Sensor Switch Sensor Indicates Lean Bank 1

Repair Importance Level: 3/3

Repair Difficulty Level: 2/3

http://engine-codes.com/p1131_ford.html

Forum Code

Possible causes

- Faulty Oxygen Sensor

- Vacuum leak affecting bank 1 only

- Fuel injector problem bank 1

- Check for cylinder misfire on bank 1

- Engine mechanical condition

Tech notes

Though the Oxygen (O2) sensor, the Engine Control Module (ECM) has detected a lean system, which means that there is either not enough fuel or and excessive amount of air in the system. Start by checking for vacuum leaks.

When is the code detected?

The Engine Control Module (ECM) detected bank 1 oxygen (O2) at its lean limit

Possible symptoms

- Engine Light ON (or Service Engine Soon Warning Light)

P1131 Ford Description

A Heated Exhaust Oxygen (HO2S) sensor 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.

Read more: http://engine-codes.com/p1131_ford.html#ixzz3izk89wMu

Aug 16, 2015 | Ford Cars & Trucks

Tip

Which Oxygen Sensor Is It?


There are many inquiries online about which oxygen sensor to change. Oxygen sensor failure codes are very common on a lot of vehicles. With all of today's vehicles having at least two oxygen sensors and many having three or four of them, it can be a little confusing as to which one is causing the problem.

Before we get into which sensor is which, we need to have a little discussion about oxygen sensor fault codes. There are several different types of oxygen sensor fault codes. Here are just some of the most common ones:

P0135 "Oxygen Sensor Heater Circuit Bank1 Sensor 1"
P0141 "Oxygen Sensor Heater Circuit Bank 1 Sensor 2"
P0147 "Oxygen Sensor Circuit Bank 1 Sensor 3"
P0152 "Oxygen Sensor Voltage High Bank 2 Sensor 1"
P0159 "Oxygen Sensor Slow Response Bank 2 Sensor 2"
P0171 "Oxygen Sensor Lean Sensor 1 Bank 1"
P0172 "Oxygen Sensor Lean Sensor 1 Bank 2"
P0174 "Oxygen Sensor Rich Sensor 1 Bank 1"
P0175 "Oxygen Sensor Rich Sensor 1 Bank 2"

There are many more possible oxygen sensor codes, but I only listed these to make my point. Many times the oxygen sensor code is NOT caused by the oxygen sensor itself. "Lean" or "Rich" oxygen sensor codes (i.e. P0171, P0174) are usually caused by something other than the oxygen sensor. Something is wrong, causing the engine to run lean (not enough fuel or too much air) or causing the engine to run rich (too much fuel or not enough air). In these cases, replacing the oxygen sensor will not fix a thing. (That is, unless you are trying to fix your bank account from having too high of a balance!) The new oxygen sensor will just set the same code as the original one. This is because the oxygen sensor is not CAUSING the problem, it is only REPORTING the problem.

High voltage codes (like P0152 above) can be caused by the oxygen sensor wires being shorted to another wire inside the wiring harness. Sometimes these codes are caused by bad grounds where some other component is trying to ground through the oxygen sensor circuit. Again, replacing the oxygen sensor will not fix this! In short, the problem needs to be diagnosed before running out and buying an oxygen sensor.

Just because a fault code has "Oxygen Sensor" or "O2 Sensor" or "O2S" in its description does not necessarily mean that an oxygen sensor needs to be replaced. Many do-it-yourselfers believe that all there is to fixing the car is to hook it to the "magic box", collect the fault codes and replace the parts the computer tells you to replace. There is nothing further from the truth.

Fault codes only point you toward which SYSTEM is failing. The system must be diagnosed to find the CAUSE of the failure. If this is not done properly, it will only result in wasting a bunch of your money. This is what you were trying to avoid by doing it yourself!

So, after reading all of the above, if you think you still want to replace an oxygen sensor, but don't know which one; here is how to figure it out:

Oxygen sensors are always numbered like this:

Bank 1 Sensor 1
Bank 2 Sensor 1
Bank 1 Sensor 2
Bank 2 Sensor 2

Some manufacturers use a kind of shorthand that reads different, but means the same thing:

Sensor 1/1 or O2s 1/1
Sensor 2/1 or O2s 2/1
Sensor 1/2 or O2s 1/2
Sensor 2/2 or O2s 2/2

Bank 1 is always the side of the engine where cylinder #1 is located and, of course, Bank 2 is the opposite side.
On a 4 cylinder engine, there is only one bank and it is always referred to as Bank 1. The exception to the 4 cylinder rule is on certain 4 cylinder engines (specifically, some Toyotas) there are two catalytic converters used. In this case, Bank 1 sensors will still be in the pipe for the catalyst that is connected to cylinder #1 and Bank 2 sensors will be in the other one.

Sensor 1 is always the "upstream" sensor (the one located BEFORE the catalytic converter).
Sensor 2 is always the "downstream" sensor (the one that is located AFTER the catalytic converter).
Sensor 3 refers to the ONLY "downstream" sensor where there are two sensors before the catalyst and only one after the catalyst. On very few vehicles the reference to this reads "Bank 1 Sensor 3".

If you do not know where cylinder #1 is, then you need to get a diagram of the firing order for your engine. Just post a question on FixYa.com and make sure you give the YEAR, MAKE, MODEL, and ENGINE SIZE of your vehicle and one or more of our experts will be happy to tell you how to find cylinder #1.

- DTTECH
ASE Certified Master Automobile Technician


Also check out this article by dttech: What Else Could Be Wrong?

on Apr 29, 2011 | Ford F-150 Cars & Trucks

1 Answer

The check engine comes on but I dont lose power the code it is showing is sid 152.does anyone know what it is.


some codes dont cause power loss or may not even notice anything wrong but a check engine light a p0152 code means following answer courtesy of OBD-CODES.com === P0152 O2 Sensor (High Voltage) OBD-II Trouble Code Technical Description Article by Dale Dale Toalston ASE Certified Technician 02 Sensor Circuit High Voltage (Bank 2 Sensor 1) What does that mean? The o2 (oxygen) sensors basically measure oxygen content in the exhaust. The PCM (powertrain control module) then uses this information to regulate fuel injector pulse. The o2 sensors are very important to proper operation of the engine. Problems with them can cause the PCM to add or take away too much fuel based on the faulty o2 sensor voltage. A P0152 code refers to the Bank 2, sensor 1, o2 sensor. (Bank 1 would contain cylinder 1 and bank 2 is the opposite bank. Bank 2 doesn't necessarily contain cylinder 2.) "Bank 2" refers to the side of the exhaust that DOES NOT contain cylinder number 1 and "Sensor 1" indicates that it is the pre-cat sensor, or forward(first) sensor on that bank. It is a four wire sensor. The PCM supplies a ground circuit and a reference voltage of about .5 volts on another circuit. Also for the o2 heater there is a battery voltage supply wire and another ground circuit for that. The o2 sensor heater allows the o2 sensor to warm up faster, thus achieving closed loop in less time than it would normally take for the exhaust to warm the sensor up to operating temperature. The O2 sensor varies the supplied reference voltage based on oxygen content in the exhaust. It is capable of varying from .1 to .9 volts, .1 indicating lean exhaust and .9 indicating rich exhaust. NOTE: A condensed explanation of fuel trims: If the o2 sensor indicates that the oxygen voltage reading is .9 volts or high, the PCM interprets this as a rich condition in the exhaust and as a result decreases the amount of fuel entering the engine by shortening injector "on time". The STFT (short term fuel trims) would reflect this change. The opposite would occur when the PCM sees a lean condition. The PCM would add fuel which would be indicated by a single digit positive STFT reading. On a normal engine the front o2 sensors switch rapidly back and forth two or three times per second and the STFT would shift positive and negative single digits to add and remove fuel to compensate at a similar rate. This little "dance" goes on to keep the air/fuel ratio at it's optimal level. Short term fuel trims or STFT reflect immediate changes in fuel injector "on-time" while long term fuel trims or LTFT reflect changes in fuel over a longer period of time. If your STFT or LTFT readings are in the positive double digits (ten or above), this indicates the fuel system has been adding an abnormal amount of fuel than is necessary to keep the proper air/fuel ratio. It may be overcompentsating for a vacuum leak or a stuck lean o2 sensor, etc. The opposite would be true if the fuel trim readings are in the negative double digits. It would indicate that the fuel system has been taking away excessive amounts of fuel, perhaps to compensate for leaking injectors or a stuck rich o2 sensor, etc. So when experiencing o2 related issues, reading your fuel trims can indicate what the PCM has been doing over the long term and short term with regard to fuel. This code indicates that the o2 sensor was stuck too high or in the rich position. The PCM monitors this voltage and if it determines that the voltage is too high out of range for too long, P0152 may set. Symptoms Symptoms may include: MIL (Malfunction Indicator Lamp) illumination Engine may run very rough Engine may be running lean or rich depending on if the o2 sensor is reading correctly or incorrectly Lack of power Increased fuel consumption Causes Potential causes of an P0152 code include: Bad bank 2, 1 o2 sensor incorrectly reading rich condition Engine running rich and o2 sensor Correctly reading rich condition Signal shorted to voltage in harness Wiring harness damage/melted due to contact with exhaust components Vacuum leak (make have lean codes (P0171, P0174) present with it) Leaking injectors Bad fuel pressure regulator Bad PCM Possible Solutions If you have any lean or rich codes associated with this code, focus on fixing these first because these can cause the o2 sensor voltage readings to appear to be faulty when they are in fact only reading correctly. So, with the engine running at operating temperature, use a scan tool to observe the Bank 2,1 o2 sensor voltage reading. Is it high? If so, look at the long term and short term fuel trim readings. The fuel trims are affected by the o2 sensors as noted above. If the LTFT reading for that bank is indicating negative double digits (PCM trying to take away fuel to compensate for problem) try inducing a vacuum leak to see if the sensor voltage then goes lean and the fuel trims increase. If the o2 sensor responds, suspect a problem with the engine, not the sensor. There may be other engine codes to help you. If the o2 sensor reading remains high (0.9 volts or above) and won't respond then shut off engine. With KOEO (Key on engine off) disconnect the o2 sensor and look for signs of corrosion or water intrustion. Repair as necessary. The voltage reading should now be about 0.5 volts. If so, replace the o2 sensor, it's shorted internally. If after unplugging the o2 sensor the voltage reading on the scan tool doesn't change, then suspect wiring problems. Inspect the harness and look for any melted wires or anywhere that the o2 sensor harness is making contact with the exhaust components. If you are unsure, you can check for continuity of all four wires between the sensor and the PCM with an ohmmeter. Any resistance at all indicates a problem. Repair as necessary.

Read more at: http://www.obd-codes.com/p0152
Copyright © OBD-Codes.com

Jul 28, 2015 | Cars & Trucks

1 Answer

I am getting the following codes on my 2002 Nissan Altima v6 3.5 liter P1430, P1420, P1805, P1152, P1102, P1011, P1021 & P1335 I'm going crazy here. Please help!


Definition of Diagnostic Trouble Code P1430 Ford: Electric Air Pump Secondary Lincoln: Electric Air Pump Secondary Mazda: Electric Air Pump Secondary Mercury: Electric Air Pump Secondary Toyota: Intake Constrictor CTRL Circuit Open or Short

Definition of Diagnostic Trouble Code P1420 Audi: Second Air Injection Valve Circ Electrical Malfunction BMW: Secondary Air Valve Control Circuit Electrical Buick: Intake Air Low Pressure Switch Circuit Low Voltage Cadillac: Intake Air Low Pressure Switch Circuit Low Voltage Chevrolet: Intake Air Low Pressure Switch Circuit Low Voltage Chrysler: Register Resonant Charging 1 (RRC1) Dodge: Register Resonant Charging 1 (RRC1) Ford: Catalyst Temperature Sensor GMC: Intake Air Low Pressure Switch Circuit Low Voltage Honda: Nox Adsorptive Catalyst System Efficiency Below Threshold Catalytic converter Jeep: Register Resonant Charging 1 (RRC1) Lincoln: Catalyst Temperature Sensor Mazda: Catalyst system efficiency below threshold (bank 1) Mercedes: AIR Pump Switch over Valve Mercury: Catalyst Temperature Sensor Oldsmobile: Intake Air Low Pressure Switch Circuit Low Voltage Pontiac: Intake Air Low Pressure Switch Circuit Low Voltage Saturn: Intake Air Low Pressure Switch Circuit Low Voltage Subaru: EVAP Purge Control Solenoid Circuit High Input Toyota: SCV Control Circuit Malfunction Volkswagen: Second Air Injection Valve Circ Electrical Malfunction

Definition of Diagnostic Trouble Code P1805 Ford: Four wheel drive high indicator circuit failure Lincoln: Four wheel drive high indicator circuit failure Mazda: (4WD) High Indicator Open Circuit Mercury: Four wheel drive high indicator circuit failure Toyota: SB Solenoid Circuit Malfunction

Definition of Diagnostic Trouble Code P1152 Audi: Bank1, Long Term Fuel Trim, Range 2 Leanness Lower Limit Exceeded BMW: Oxygen Sensor Heater Circuit Low Voltage (Bank 2 Sensor 1) Ford: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Rich Jaguar: Lack of H02S-21 switch, sensor indicates rich Land Rover: Oxygen sensor response time bank 2.Short circuit to ground Lincoln: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Rich Mazda: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Rich Mercury: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Rich Subaru: Oxygen sensor range /performance problem (Low) Volkswagen: Bank1, Long Term Fuel Trim, Range 2 Leanness Lower Limit Exceeded Volvo: Oxygen Sensor Front, Bank 2

Definition of Diagnostic Trouble Code P1102 Acura: Mass Airflow (MAF) Sensor Lower Than Expected Comprehensive Audi: Oxygen Sensor Heating Circuit,Bank1-Sensor1 Short to B+ Chrysler: HEV Stop Request Performance Dodge: HEV Stop Request Performance Hyundai: MAP Sensor Circuit Low Input Jeep: HEV Stop Request Performance Kia: Heated Oxygen Sensor Bank 1 Sensor 1 Heater Circuit High Input Land Rover: Throttle to air flow plausibility not active.Last occurrence - minimum signal Mazda: Mass Air Flow Sensor In Range But Lower Than Expected Mitsubishi: Traction Control Ventilation Solenoid Circuit Porsche: Heated Oxygen Sensor 1 Ahead Of TWC Heater Short To B+ Saab: Front Heated Oxygen Sensor Bank 1, Control Module Input, Current in Pre-Heating Circuit Too High Subaru: Pressure Sources Switching Solenoid Valve Circuit Malfunction Volkswagen: Oxygen Sensor Heating Circuit,Bank1-Sensor1 Short to B+ Volvo: Power Stage Group B

Definition of Diagnostic Trouble Code P1011 Saab: Injector Cylinder 1 Shorting To Ground Toyota: OCV for VVTL Open Malfunction (Bank 1)

Definition of Diagnostic Trouble Code P1021 Honda: Valve Pause System Stuck On Comprehensive Mitsubishi: OCV OPN. Bank 1 Saab: Injector Cylinder 2 Shorting To Ground Toyota: OCV for VVTL Open Malfunction (Bank 2)

Definition of Diagnostic Trouble Code P1335 Audi: Engine Torque Monitoring 2 Control Limit Exceeded Buick: CKP Circuit Cadillac: CKP Circuit Chevrolet: CKP Circuit Ford: (EGR) Position Sensor Minimum Stop Performance GMC: CKP Circuit Infiniti: CKP Sensor (Ref) Jaguar: CKPS Circuit Malfunction Land Rover: Exhaust gas recirculation position sensor minimum stop performance. Lexus: Igniter Circuit Malfunction Bank 2 (During Engine Running) Lincoln: (EGR) Position Sensor Minimum Stop Performance Mazda: (EGR) Position Sensor Minimum Stop Performance Mercedes: CKP Sensor Circuit Malfunction, Bank 2 Mercury: (EGR) Position Sensor Minimum Stop Performance Oldsmobile: CKP Circuit Pontiac: CKP Circuit Saturn: CKP Circuit Toyota: No CKP Sensor Signal Engine Running Volkswagen: Engine Torque Monitoring 2 Control Limit Exceeded http://www.obd-codes.com/trouble_codes/nissan

Jun 29, 2015 | Nissan Cars & Trucks

1 Answer

2006 pacifica


Car may be running rich. If the car is getting normal mpg, I would not worry. The codes that indicate poor converter efficiency indicate the converter is wearing out. If that code keeps coming back, replace the converter. If it is getting poor mpg, I would look for something causing rich operation. Possibly a broken fuel pressure regulator or maybe a bad map sensor. Continued rich operation will cause the converter to fail prematurely.

Jul 14, 2017 | 2006 Chrysler Pacifica Touring

1 Answer

Code 1150 on a 1997 ford f 150 with a 4.2 motor


I will try to paste an article for you. Several sources indicate this is a Bank 2 O2 sensor problem and that it is failing to switch and adjust for the fuel mix. But as you can see, many defects can lead up to this O2 sensor Code 1150.

I would try to use a spray bottle of water and go around the Intake manifold and spray the water while the engine is running. An intake leak will draw water into the engine and change RPM.

If no success then try changing the O2 bank 2 sensor. You may need to wipe the computer and clear the Code. H40 DTCs P1131, P1132, P1151 AND P1152: UPSTREAM HO2S NOT SWITCHING. DTC P1130: FUEL SYSTEMicon1.png NOT SWITCHING AT FUELicon1.png TRIM (RICH OR LEAN)
Diagnostic Trouble Codes (DTCs) P1131 bank 1 (Cylinder 1) and P1151 bank 2 indicate the fuel/air ratio is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt. DTCs P1132 bank 1 (Cylinder 1) and P1152 bank 2 indicate the fuel/air ratio is correcting lean for an overly rich condition. The HO2S voltage is greater than 0.45 volt.
DTC P1130 and P1150 indicate the fuel control system has reached maximum compensation for a lean or rich condition and the HO2S is not switching.
DTC/HO2S Reference List
•HO2S-11 = DTCs P1131, P1132 and P1130
•HO2S-21 = DTCs P1151, P1152 and P1150
Possible causes:
Fuel system
•Excessive fuel pressure.
•Leaking fuel injector(s).
•Leaking fuel pressure regulator.
•Low fuel pressure or running out of fuel.
•Contaminated fuel injector(s)
•Vapor recovery system
Induction system
•Air leaks after the MAF.
•Vacuum leaks (vacuum lines and gaskets).
•Restricted air inlet.
•PCV system.
•Improperly seated engineicon1.png oil dipstick.
EGR System
•Leaking gasket.
•Stuck open EGR valve.
•Leaking diaphragm.
Base engine
•Oil overfill.
•Cam timing.
•Cylinder compression.
•Exhaust leaks before or near the HO2Ss.
•Check intake air system for leaks, obstructions and damage.
•Check air cleaner element, air cleaner housing for blockage.
•Verify integrity of the PCV system.
•Check for vacuum leaks. user_online.gif quote.gif post_old.gif )

Mar 28, 2013 | 2003 Ford Ranger Regular Cab

1 Answer

Error codes po152 and po442


Hi there:
DTC P0152 - 02 Sensor Circuit High Voltage (Bank 2 Sensor 1)
The o2 (oxygen) sensors basically measure oxygen content in the exhaust. The PCM (powertrain control module) then uses this information to regulate fuel injector pulse. The o2 sensors are very important to proper operation of the engine. Problems with them can cause the PCM to add or take away too much fuel based on the faulty o2 sensor voltage.

A P0152 code refers to the Bank 2, sensor 1, o2 sensor. (Bank 1 would contain cylinder 1 and bank 2 is the opposite bank. Bank 2 doesn't necessarily contain cylinder 2.) "Bank 2" refers to the side of the exhaust that DOES NOT contain cylinder number 1 and "Sensor 1" indicates that it is the pre-cat sensor, or forward(first) sensor on that bank. It is a four wire sensor. The PCM supplies a ground circuit and a reference voltage of about .5 volts on another circuit. Also for the o2 heater there is a battery voltage supply wire and another ground circuit for that. The o2 sensor heater allows the o2 sensor to warm up faster, thus achieving closed loop in less time than it would normally take for the exhaust to warm the sensor up to operating temperature.
The O2 sensor varies the supplied reference voltage based on oxygen content in the exhaust. It is capable of varying from .1 to .9 volts, .1 indicating lean exhaust and .9 indicating rich exhaust. NOTE: A condensed explanation of fuel trims: If the o2 sensor indicates that the oxygen voltage reading is .9 volts or high, the PCM interprets this as a rich condition in the exhaust and as a result decreases the amount of fuel entering the engine by shortening injector "on time". The STFT (short term fuel trims) would reflect this change. The opposite would occur when the PCM sees a lean condition. The PCM would add fuel which would be indicated by a single digit positive STFT reading. On a normal engine the front o2 sensors switch rapidly back and forth two or three times per second and the STFT would shift positive and negative single digits to add and remove fuel to compensate at a similar rate. This little "dance" goes on to keep the air/fuel ratio at it's optimal level. Short term fuel trims or STFT reflect immediate changes in fuel injector "on-time" while long term fuel trims or LTFT reflect changes in fuel over a longer period of time. If your STFT or LTFT readings are in the positive double digits (ten or above), this indicates the fuel system has been adding an abnormal amount of fuel than is necessary to keep the proper air/fuel ratio. It may be overcompentsating for a vacuum leak or a stuck lean o2 sensor, etc. The opposite would be true if the fuel trim readings are in the negative double digits. It would indicate that the fuel system has been taking away excessive amounts of fuel, perhaps to compensate for leaking injectors or a stuck rich o2 sensor, etc. So when experiencing o2 related issues, reading your fuel trims can indicate what the PCM has been doing over the long term and short term with regard to fuel.
This code indicates that the o2 sensor was stuck too high or in the rich position. The PCM monitors this voltage and if it determines that the voltage is too high out of range for too long, P0152 may set.

Symptoms may include:MIL (Malfunction Indicator Lamp) illuminationEngine may run very roughEngine may be running lean or rich depending on if the o2 sensor is reading correctly or incorrectlyLack of powerIncreased fuel consumption

Potential causes of an P0152 code include:Bad bank 2, 1 o2 sensor incorrectly reading rich conditionEngine running rich and o2 sensorCorrectly reading rich conditionSignal shorted to voltage in harnessWiring harness damage/melted due to contact with exhaust componentsVacuum leak (make have lean codes (P0171, P0174) present with it)Leaking injectorsBad fuel pressure regulatorBad PCM

Possible Solutions:If you have any lean or rich codes associated with this code, focus on fixing these first because these can cause the o2 sensor voltage readings to appear to be faulty when they are in fact only reading correctly.
So, with the engine running at operating temperature, use a scan tool to observe the Bank 2,1 o2 sensor voltage reading. Is it high? If so, look at the long term and short term fuel trim readings. The fuel trims are affected by the o2 sensors as noted above. If the LTFT reading for that bank is indicating negative double digits (PCM trying to take away fuel to compensate for problem) try inducing a vacuum leak to see if the sensor voltage then goes lean and the fuel trims increase. If the o2 sensor responds, suspect a problem with the engine, not the sensor. There may be other engine codes to help you.
If the o2 sensor reading remains high (0.9 volts or above) and won't respond then shut off engine. With KOEO (Key on engine off) disconnect the o2 sensor and look for signs of corrosion or water intrustion. Repair as necessary. The voltage reading should now be about 0.5 volts. If so, replace the o2 sensor, it's shorted internally.
If after unplugging the o2 sensor the voltage reading on the scan tool doesn't change, then suspect wiring problems. Inspect the harness and look for any melted wires or anywhere that the o2 sensor harness is making contact with the exhaust components. If you are unsure, you can check for continuity of all four wires between the sensor and the PCM with an ohmmeter. Any resistance at all indicates a problem. Repair as necessary.

DTC P0442 - Evaporative Emission Control System Leak Detected (small leak)
This indicates a fuel vapor leak in the EVAP control system. It means a very small leak has been detected. In fact, the leak can be from a hole as small as 0.04" in diameter. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.


A code P0442 most likely means one or more of the following has happened:A loose or improperly affixed gas capA non-conforming gas cap (i.e. not factory/original brand)A small leak/hole in a fuel vapor hose/tubeOther small leak in EVAP systemFaulty vent o-ring seal

With a P0442, the most common repair is to:Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.Otherwise, replace the gas cap, orInspect the EVAP system for cuts/holes in tubes/hoses

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Mar 28, 2012 | 2001 Jeep Grand Cherokee

1 Answer

I have a 1996 silverado with the 5.7l vortec engine. My Service engine soon light came on today so i took my truck to advance. They read a code PO172-System running rich (bank 1) and my exhaust has a...


the code indicates a bank 1problem.so anything that is common between both sides of the motor will not set this code,if anything it would set a different code and show a common code for both sides of the motor,vacuum leak would not be the problem as it would also affect the way the motor runs,bad /dirty maf sensor again affects both sides and a code difference,bad coolant again affects both sides and different code,an 02 sensor can show which side the problem is and could cause the setting code.bad spark plugs can also cause this code, an injector one or more for this side can cause this,bad fuel pressure regulator will affect both sides again.so I would check spark plugs, check the 02 sensor for proper voltage readings on the left side of the motor(driver`s side),it`s uncommon for injectors on one side to only go bad and not injectors on both sides.if the plugs are okay and don`t need changing you may need to check for tune-up items such as plug wires.it sounds like the motor is not burning the fuel properly giving the rich running code

Mar 10, 2011 | Chevrolet 1500 Cars & Trucks

2 Answers

I am thinking about buying a 1996 ford taurus from my grandmother but the check engine light is on. I have taken it to the parts store and had a diagnostic run and they told me that it read p1131 and...


Those codes are for a "lack of switching" on the heated oxygen sensors. First thing to look at is the the MAF sensor. It is in the intake hose after the air filter but before the intake manifold. take it out and clean it with ELECTRONICS cleaner only DO NOT use carb/brake cleaner. Let it dry for 15-20 minutes and then re-install. Disconnect the positve battery cable to clear the code and then drive it. If the light comes back on and the same code is retrieved then you might have a bad MAF sensor.

Jan 01, 2011 | Ford Taurus Cars & Trucks

1 Answer

Engine light keeps coming on. and when I did test they said bank 1 and bank 2 is running rich. what does this usually mean. Dealer says it is safe to drive until I get it fix, but I am burning alot of gas...


What that means, as you have noticed, is that you have a problem with the vehicle which is causing the computer to deliver more fuel than needed to the engine. Running Rich = too much fuel. Running Lean = too little fuel. There are many reasons why your engine would be running rich, and could be anything from a malfunctioning sensor to a vacuum leak to a leak in the exhaust ahead of the oxygen sensor.

You can drive it while running rich temporarily, but it can cause issues with fouling the spark plugs and damaging the catalytic converter over time.

Dec 18, 2009 | 2004 Kia Sedona

Not finding what you are looking for?
Cars & Trucks Logo

196 people viewed this question

Ask a Question

Usually answered in minutes!

Top Mercedes-Benz Experts

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

yadayada
yadayada

Level 3 Expert

75117 Answers

Michael Contreras
Michael Contreras

Level 2 Expert

166 Answers

Are you a Mercedes-Benz Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...