Lack of H02521 switch fuel trim at limit

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

Definition of Diagnostic Trouble Code P1506 Audi: Closed Throttle Position Switch Does Not Open/Short to Ground BMW: Idle-Speed Control Valve Opening Solenoid Control Circuit Signal High Ford: Idle Air Control Overspeed Error (see P0507) Jaguar: Idle Air Control System RPM Lower Than Expected - B Bank Kia: IAC Valve Opening Coil Voltage High Lincoln: Idle Air Control Overspeed Error (see P0507) Mazda: Idle Air Control Overspeed Error Mercury: Idle Air Control Overspeed Error (see P0507) Porsche: Throttle Jacking Unit Lower Mechanical Stop, Signal Implausible Volkswagen: Closed Throttle Position Switch Does Not Open/Short to Ground Volvo: IAC Valve Opening Signal
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Definition of Diagnostic Trouble Code P1151 Audi: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded BMW: Oxygen Sensor Heater Circuit Signal Intermittent (Bank 2 Sensor 1) Ford: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Jaguar: Lack of H02S-21 switch, sensor indicates lean Land Rover: Lambda control limit bank 2.Implausible signal/condition Lincoln: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mazda: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Mercury: Lack Of Heated Oxygen Sensor Bank 2 Sensor 1 Switches - Sensor Indicates Lean Subaru: HO2S-12 Heater Circuit High Input Toyota: Coolant Path Clog Up for Coolant Heat Storage System Volkswagen: Bank1, Long Term Fuel Trim, Range 1 Leanness Lower Limit Exceeded
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Definition of Diagnostic Trouble Code P0302 Category: Powertrain Definition: Cylinder 2 Misfire DetectedNote: This definition of P0302 is applied to all manufacturers
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Definition of Diagnostic Trouble Code P0171 Category: Powertrain Definition: System Too Lean Bank 1Note: This definition of P0171 is applied to all manufacturers

P0156 - Problem with 0/2 circuit for downstream sensor of the front bank.
P1131 - Low activity of the upstream sensor for bank one. (rear)
P0115 - Problem with circuit for coolant temp sensor.

Just because you have codes for these sensors doesn't mean the sensor is the reason. The code merely tells you there is an issue in the circuit that needs to be troubleshooted accurately.

P0171 ; Fuel Trim System Lean (Bank 1)
P0174; Fuel Trim too Lean (Bank 2)
fuel trim is system to modify injector pulse if system go lean it will go rich when the system is too much lean and is max.rich it code
look for 02 sensor bank 1 and 2 data
hope it helps

I don't care how handy you are , that's not going to help you unless you have knowledge of OBD 2 engine management system for your vehicle . Plus having diagnostic test equipment , scan tool to view engine sensor data ., an knowing how to do automotive electrical circuit testing.
Po171 Could be just an O2 sensor problem ,looking at scan data for bank 1 sensor 1 for proper switching , could be a easy find for a trained Tech . You on the other hand could spend hundreds an still not fix the problem .

P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:

• 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 MAF.
  • Vacuum Leaks.
  • PCV system.
  • Improperly seated engine oil dipstick.
• EGR system:
  • Leaking gasket.
  • Stuck EGR valve.
  • Leaking diaphragm or EVR.
• Base Engine:
  • Oil overfill.
  • Cam timing.
  • Cylinder compression.
  • Exhaust leaks before or near the HO2Ss.

P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• Electrical:
  • Short to VPWR in harness or HO2S
  • Water in harness connector
  • Open/Shorted HO2S circuit
  • Corrosion or poor mating terminals and wiring
  • Damaged HO2S
  • Damaged 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 MAF
  • Vacuum Leaks
  • PCV system
  • Improperly seated engine oil dipstick
• EGR System:
  • Leaking gasket
  • Stuck EGR valve
  • Leaking diaphragm or EVR
• Base Engine:
  • Oil overfill
  • Cam timing
  • Cylinder compression
  • Exhaust leaks before or near the HO2S(s)

A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S. P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean A HEGO sensor 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. See Possible Causes for DTC P1130
P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130 006 O2 Sensor Signal Analysis

I've come across these codes before. In almost every case there was an air leak in the intake air hose (hose between the engine air filter & the throttle body). Inspect this hose & tubes attached to it. This is especially true when the lean code includes the comment 'at idle'
P2187 - System too lean at idle Bank 1
P0174 - System too lean Bank 2
P2189 - System too lean at idle Bank 2
P2195 = HO2S Signal Biased/Stuck Lean (Bank 1 Sensor 1)
P2270 = HO2S Signal Stuck Lean (Bank 1 Sensor 2)
P2272 = HO2S Signal Stuck Lean (Bank 2 Sensor 2)

P2187 & P2189 = In order to provide the best possible combination of drivability, fuel economy and emission control, the PCM uses a closed loop air/fuel metering system. The PCM monitors the HO2S signal voltage and adjusts fuel delivery based in closed loop fuel control. Changes in fuel delivery will be indicated by the long-term and the short-term fuel trim values. The ideal fuel trim value is around 0%. The PCM will add fuel when the HO2S signal is indicating a lean condition. Additional fuel is indicated by fuel trim values that are above 0%. The PCM will reduce fuel when the HO2S signal is indicating a rich condition. Reduction in fuel is indicated by fuel trim values that are below 0%. The DTC relevant to fuel trim will be set when the amount reaches excessive levels because of a lean or rich condition

P0171 - System to Lean (Bank 1)
P0174 - System to Lean (Bank 2) Lack of fuel or too much air - unmetered air after the mass air flow sensor ! vacuumn leak . Not enough fuel - low fuel pressure , clogged injectors .
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information. Air Measurement System

• MAF sensor (contaminated, damaged, malfunctioning, etc.)

Fuel System

• Fuel pressure regulator (leaking, malfunctioning, etc.).
• Fuel filter plugged, dirty.
• Fuel pump (weak, check valve leaking, etc.).
• Leaking/contaminated fuel injectors.
• Low fuel pressure or running out of fuel.
• EVAP canister purge valve leaking (when canister is "clean").
• Fuel supply line restricted.
• Fuel rail pressure sensor (incorrect reading).

Air Induction System

• Air leaks after the MAF.
• Vacuum Leaks.
• PCV system (leak, valve stuck open, etc.)
• Improperly seated engine oil dipstick.

Exhaust System

• Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.)..

EGR System

• EGR valve tube/gasket leak
• EVR solenoid vacuum leak

Secondary Air Injection

• Damaged/malfunctioning secondary air injection system (mechanically stuck valve).

View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s). Refer to Section 2 , Adaptive Fuel DTCs Diagnostic Techniques for more information.
P0457 - EVAP Control System Leak Detected (Fuel Filler Cap Loose/Off) A fuel tank pressure change less than a minus (-) 7 inches of H 2 0 in 30 seconds has occurred after refueling; or there is excessive purge (fuel vapor) flow greater than 0.06 pounds per minute.

• Fuel filler cap not installed on refueling (storing continuous memory DTC) and "Check Fuel Cap" light may also be illuminated.
• Fuel filler cap missing, loose or cross-threaded.

Check for missing fuel filler cap or integrity of the cap. If OK, clear continuous memory DTCs and re-initiate EVAP Emission Running Loss Monitor Drive Cycle.
Stuck open evap purge valve , maybe. Take your vehicle to a qualified repair shop an have the evap system smoke tested .

P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130

Get a PCM test for fault codes. It could be an oxygen sensor or MAF sensor. Free test at AUtozone if check engine light is on.
Clean MAF sensor heated wires with carb cleaner by spraying seveal times. Do not brush it. Disconnect battery for 2 hours and then drive for 10 miles after hook up.

SERVICE TIP MASS AIR FLOW (MAF) DISCUSSION MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows. If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF sensor is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads. One of the indicators for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT (there is no actual BARO sensor on MAF-equipped vehicles, except for the 3.8L Supercharged engine). At high air flows, a contaminated MAF sensor will under-estimate air flow coming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle. NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs. Symptoms

• Lack of Power
• Spark Knock/Detonation
• Buck/****
• Hesitation/Surge on Acceleration
• Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory

OBDII DTCs

• P0171, P0174 (Fuel system lean, Bank 1 or 2)
• P0172, P0175 (Fuel system rich, Bank 1 or 2)
• P1130, P1131, P1132, (HO2S11 lack of switching, Bank 1)
• P1150, P1151, P1152, (HO2S21 lack of switching, Bank 2)

OBDI DTCs

• 181, 189 (Fuel system lean, Bank 1 or 2)
• 179, 188 (Fuel system rich, Bank 1 or 2)
• 171, 172, 173 (HO2S11 lack of switching, Bank 1)
• 175, 176, 177 (HO2S21 lack of switching, Bank 2)
• 184, 185 (MAF higher/lower than expected)
• 186, 187 (Injector pulse width higher/lower than expected)

NOTE: DO NOT DISCONNECT THE BATTERY. IT WILL ERASE KEEP ALIVE MEMORY AND RESET LONG TERM FUEL TRIM AND BARO TO THEIR STARTING/BASE VALUES. THE BARO PARAMETER IDENTIFICATION DISPLAY (PID) IS USED FOR THIS DIAGNOSTIC PROCEDURE. ALL OBDII APPLICATIONS HAVE THIS PID AVAILABLE. THERE ARE SOME OBDI VEHICLES THAT DO NOT HAVE THE BARO PID, FOR THESE VEHICLES OMIT THE BARO CHECK AND REFER ONLY TO STEPS 2, 3, AND 4 IN THE DIAGNOSTIC PROCEDURE.

1. Look at the BARO PID. Refer to the Barometric Pressure Reference Chart in this article. At sea level, BARO should read about 159 Hz (29.91 in. Hg). As a reference, Denver, Colorado at 1524 meters (5000 ft.) altitude should be about 144 Hz (24.88 in. Hg.). Normal learned BARO variability is up to ±6 Hz (±2 in. Hg.). If BARO indicates a higher altitude than you are at (7 or more Hz lower than expected), you may have MAF contamination. If available, Service Bay Diagnostic System (SBDS) has a Manifold Absolute Pressure (MAP) sensor that can be used as a barometric pressure reference. Use "MAP/BARO" test under "Powertrain," "Testers and Meters." Ignore the hookup screen. Connect GP2 to the reference MAP on the following screen. NOTE: REMEMBER THAT MOST WEATHER SERVICES REPORT A LOCAL BAROMETRIC PRESSURE THAT HAS BEEN CORRECTED TO SEA LEVEL. THE BARO PID, ON THE OTHER HAND, REPORTS THE ACTUAL BAROMETRIC PRESSURE FOR THE ALTITUDE THE VEHICLE IS BEING OPERATED IN. LOCAL WEATHER CONDITIONS (HIGH AND LOW PRESSURE AREAS) WILL CHANGE THE LOCAL BAROMETRIC PRESSURE BY SEVERAL INCHES OF MERCURY (±3 Hz, ±1 in. Hg.). NOTE: BARO IS UPDATED ONLY WHEN THE VEHICLE IS AT HIGH THROTTLE OPENINGS. THEREFORE, A VEHICLE WHICH IS DRIVEN DOWN FROM A HIGHER ALTITUDE MAY NOT HAVE HAD AN OPPORTUNITY TO UPDATE THE BARO VALUE IN KAM. IF YOU ARE NOT CONFIDENT THAT BARO HAS BEEN UPDATED, PERFORM THREE OR FOUR HEAVY, SUSTAINED ACCELERATIONS AT GREATER THAN HALF-THROTTLE TO ALLOW BARO TO UPDATE.
   

if sensor indicates lean check the fuel trim if long term fuel trim is above +7 them test sensor with a piko lab scope or watch scan data and create a rich condtion by snping the throttle wide open and watch the sensor if it start to read around 700to 900mv its ok, then create a vacume leak and the sensor should read 100to 300mv i your sensor is in this range quickly its good with in 1to2 sec.

Lack of HO2S-11 Switch, Indicates Lean.Right bank front 02 sensor. When an HO2S sensor indicates lean at the end of a test, the system is trying to correct for an over-lean condition. The code is set when the fuel control system no longer detects switching for a calibrated amount of time.In other words the 02 sensor is indicating lean and the fuel trim has reached the programed limit trying to correct it.
There are many things that could cause this like a bad 02 sensor,a vacuum leak,a leaking or contaminated fuel injector/s,a stuck open PCV valve,leak in hose between MAF sensor and engine causing un-metered or unmeasured air entering the engine,exhaust leak,improperly seated oil dipstick,stuck EGR valve.
Check PCV valve first if it is stuck open if you pull the hose off of the valve cover that hooks to the air tube between MAF and engine you will feel a strong vacuum pull there,normal you would hardly feel it.