Automotive Answerman
 Possible Causes
MAF System Performance  
Faulty sensor,short/open to pcm.vpwr circuit open to sensor,intake air leak near sensor,sensor disconnected,Faulty PCM
MAF Sensor Circuit- Low Frequency 
MAF return cicuit open to PCM,-MAF Sensor shorted to ground.
 P0103  MAF - Sensor Circuit - High Frequency  Check for condition and proper seating of connections at PCM and MAF Sensor,Check for water/moisture in air induction system or MAF Sensor,Check for short to voltage,Faulty MAF Sensor 
 P0107  MAP - Sensor Circuit - Low Voltage Check with DVOM- MAP Sensor signal wire for Open,Check for Short to Ground on same circuit,Check for high resistance on circuit,Faulty connections or wiring,Faulty MAP Sensor. 
 P0108  MAP - Sensor Circuit - High Voltage Check for Short to Voltage on MAP sensor signal wire between PCM and Sensor,Check for Vacuum Leaks,Restrictions in vacuum supply,Faulty seating of sensor,Faulty connections or wiring,Faulty MAP Sensor,Faulty PCM 
 P0112  IAT - Sensor Circuit - Low Voltage Open or grounded circuit in harness,Sensor connector broken or loose,Faulty Sensor,Faulty PCM 
 P0113  IAT - Sensor Circuit - High Voltage Faulty Sensor,Loose or broken connection,short to VPWR,Faulty PCM, Always do a wiggle test-wiggle wire loom to sensor in short sections to check for short.
 P0117  ECT - Sensor Circuit - Low Voltage ECT circuit grounded,Faulty connection, Faulty ECT Sensor, Faulty PCM, Referance voltage 4-6 volts 
 P0118  ECT - Sensor Circuit - High Voltage Indicates Max self test voltage,Sensor circuit short to power,Open circuit in harness or connector,Faulty Sensor,Faulty PCM. 
 P0121  TP - Sensor Performance  Check connections,Using DVOM resistance if less than 5ohms replace sensor, If more than 5ohms repair open in wire 
 P0122  TP - Sensor Circuit - Low Voltage Indicates voltage is below self test limit,Check for sensor not properly seated,TP circuit open to PCM, VREF open to TP Sensor,TP circuit shorted to Return signal or ground,Faulty Sensor, Faulty PCM  
 P0123  TP - Sensor Circuit - High Voltage Indicates voltage is above self test limit,Check for sensor not properly seated,TP circuit shorted to VPWR,Signal RTN circuit open to TP sensor,Faulty TP sensor Faulty PCM 
 P0125  ECT - Excessive Time To Enter Closed Loop Fuel Control  PCM monitors engine warm-up time, Check for thermostate stuck open,Engine warm up time insufficent,Faulty ECT Sensor,Low engine coolant. 
 P0128  ECT - Less Then Thermostat Regulating Temperature  Check for thermostate stuck open or leaking,Low engine coolant,Faulty ECT Sensor,Faulty IAT Sensor(Intake Air Temperature),Cooling fan running excessively(ie- Longer than normal). 
 P0131  HO2S - Circuit Low Voltage - Bank 1 - Sensor 1 Check resistance between suspect O2 and PCM if 5 ohms or les Replace O2 if more then 5ohms repair wire between PCM and suspect O2 Same for P0151,P0137&P0157
 P0132  HO2S - Circuit High Voltage - Bank 1 - Sensor 1 Check O2 Circuit Voltage-Disconnect O2 connector turn ignition on,With a DVOM test voltage if .5 or less replace O2 sensor if more repair short.Test resistance if 10K/ohms or replace PCM if less than 10K/ohms repair short between PCM and sensor.  
 P0133  HO2S - Slow Respones - Bank 1 - Sensor 1  Upstream O2 Sensors Check for Sensor contamination,Exhaust Leaks,Open or shorted ciruit,Improper fuel,Leak in air induction system,Deteriorating O2 sensor,Faulty MAF Sensor.Same for P0153
 P0134  HO2S - Circuit Insufficient Activity - Bank 1 - Sensor 1 Always Check Fuses and Connections/Wires if good Replace suspect O2 Sensor-Same for P0140,P0154, and P0160 
 P0135  HO2S - Heater Performance - Bank 1 - Sensor 1 Indicates short to VPWR,OpenVPWR or Ground Circuit in O2 heater circuit,Check for moisture in connectors,corroded or damaged connections or wires, Low Battery Voltage,Faulty O2 Sensor,Faulty PCM. Same for P0155.P0141. and P0161. 
 P0137  HO2S - Circuit Low Voltage - Bank 1 - Sensor 2 ***NOTE" REFER TO P0131"*** 
 P0138  HO2S - Circuit High Voltage - Bank 1 - Sensor 2 ***NOTE"REFER TO P0132"*** 
 P0140  HO2S - Circuit Insufficient Activity - Bank 1 - Sensor 2 ***NOTE"REFER TO P0134"*** 
 P0141  HO2S - Heater Performance - Bank 1 - Sensor 2 ***NOTE"REFER TO P0135"*** 
 P0151  HO2S - Circuit Low Voltage - Bank 2 - Sensor 1 ***NOTE "REFER TO P0131"*** 
 P0152  HO2S - Circuit High Voltage - Bank 2 - Sensor 1 ***NOTE"REFER TO P0132"***
 P0153  HO2S - Slow Response - Bank 2 - Sensor 1 ***NOTE"REFER TO P0133"***
 P0154  HO2S - Circuit No Activity Detected - Bank 2 - Sensor 1 ***NOTE"REFER TO P0134"*** 
 P0155  HO2S - Heat Circuit - Bank 2 - Sensor 1 ***NOTE"REFER TO P0135"*** 
 P0157  HO2S - Circuit Low Voltage - Bank 2 - Sensor 2 ***NOTE"REFER TO P0131"*** 
 P0158  HO2S - Circuit High Voltage - Bank 2 - Sensor 2 ***NOTE"REFER TO P0132"***
 P0160  HO2S - Circuit Insufficient Activity - Bank 2 - Sensor 2  ***NOTE"REFER TO P0134"*** 
 P0161  HO2S - Heater Circuit - Bank 2 - Sensor 2 ***NOTE"REFER TO P0135"*** 
 P0171  Fuel System Too Lean - Bank 1 Lean condition, Check for Low fuel pressure,Out of fuel,Vaccum Leaks in engine/Intake,Exhaust Leaks at or near O2 Sensors,Low cylinder Compression.-Same for P0174 
 P0172  Fuel System Too Rich - Bank 2

 Rich Condition, Check for High fuel pressure,Leaking Injectors,EGR System,PCV system,EVR system,Engine oil overfill,Improperly seated oil dipstick,CAM Timing,Faulty MAF Sensor,Same for P0175

 P0174 System Too Lean - Bank 2 

 ***NOTE"REFER TO P0171"***

 P0175 System Too Rich - Bank 2 

 ***NOTE"REFER TO P0172"***

 P0201 - P0210 Injector Control Circuits -Cyclenders 1 - 10 (Respectively) 

Faulty Inector, Wiring from PCM to Injector,Faulty PCM,Swap suspect injector with known good injector(ie-the one next to suspect if no code pesent) if code follows Replace injector.Cylinder specific code P0201=cyl 1, P205=cyl 5. ect  

P0230  Fuel Pump Relay Control Circuit 

 Check for short to ground on control circuit,Fuel pump control circuit open, Short to battery voltage on control circuit,Chaffed or frayed wiring,Faulty Relay, Faulty PCM.

 P0300 Engine Misfire Detected 

 Random or Multiple cylinder misfire,Check for faulty plugs, Plug wires,O2 Sensors,Fuel injectors,Burnt valves-(ie-compression) Catalytic converter,Stuck or obstructed EGR, Cam Sensor, Coil/coils,Faulty PCM

 P0301 - P0310 Engine Misfire Detected Cyclinders 1 - 10 (Respectively) 

 Cylinder Specific - (ie- P0301= cyl 1 & P0305 = cyl 5) ***NOTE"REFER TO P0300"*** for possible causes.

 P0325 Knock Sensor Module Circuit  

 Faulty knock sensor, Faulty circuit wiring, Check sensor resistance to factory specifications

 P0327 & P0332 Knock Sensor Circuit - Bank 1 & Bank 2 (Respectively) 

 Fauty knock sensor, Faulty circuit wiring, P0327=cyl  1 & P0332= cyl 2 (voltage should be 5 volts)

P0335  Crankshaft Position Sensor Circuit 

Faulty or Damaged sensor/connector, Open,Shorted,or Grounded sensor output, Damaged or missing teeth on ring gear, Timing belt or chain, Faulty PCM. 

P0341 Camshaft Position Sensor Circuit 

 Check all circuit wiring may be frayed or broken shorting out,Check timing,Faulty cam sensor,Faulty crank sensor,Faulty PCM, *NOTE* Route cam circuit wires away from plug wires as interference may occur.

P0342  Camshaft Postion Signal Low 

 Check for open,grounded,or frayed wires, Faulty Sensor, Faulty PCM, or reluctor ring.

P0343 Camshaft Postion Signal High 

 Check for short to VPWR or VREF feed, Check connections at PCM/Sensor,Faulty sensor, Faulty PCM.

 P0351 & P0358 Ignition Control Circuit 

Check for Open in coil driver circuit,Short to Voltage or Ground,Faulty or damaged connections/wires,Faulty coil, Faulty PCM. 

P0401  EGR - System Insufficient Flow 

Check for blockage in EGR or circulation tubes-most often carbon buildup preventing recirculation,Faulty DPFE-Differential feedback EGR Sensor,EGR Stuck or not opening Check Vacuum,Faulty EGR,

P0403 EGR - Solenoid Control Circuit 

 Check for Voltage loss to EGR Solenoid,To much resistance in Control circuit to EGR,Obstruction holding solenoid open(ie-Carbon build up),Loose or damaged connections,Faulty EGR Solenoid, Faulty PCM.

P0404 EGR - Open Position Performance 

 When EGR is electrically operated Check 5 volt reference for short,Check Ground circuit for Open or short,Blocked or Obstruction in EGR system,Faulty PCM.

P0405  EGR - Position Sensor Circuit - Low Voltage 

 Check for short to Ground,Short to Voltage,Test for 5 volt reference and Ground using DVOM,Loose or damaged wiring/connections,Faulty PCM.

P0410 Secondary Air Injection (AIR) System

Check power to pump (ie-Blown Fuse), Check for loose or damaged wires or connections,Check pump for corrosion or wear,Check for water accumulation in pump or check valve. 

P0412 Secondary Air Injection (AIR) Solenoid Relay Control  Circuit  

 PCM Controlled-Check for short to Ground, Check for short to voltage in control circuit,Check for Open/Short in Battery circuit to the solenoid,Check for Open/Short in relay control circuit.

 P0420 & P0430 Catalyst System Low Efficiency - Bank 1 & 2 (Respectively)  

Faulty or damaged O2 Sensor,Faulty coolant sensor,Timing retarded,Leaking Injector,Leaking exhaust system,Exhaust system contamination (ie-Oil/Coolant), Cylinder misfire,Faulty Catalytic Converter,P0420= Bank 1 & P0430= Bank 2. 

P0440  EVAP System  

 General EVAP failure,Most cases Gas Cap loose not properly seated,Check for blockage in the charcoal canister,Faulty purge solenoid.

P0442 EVAP Control System Small Leak Detected 

 Check vapor/vacuum lines-Fuel vapors accelerate deterioration,Check gas cap,Faulty vent solenoid O-Ring.

P0443 EVAP Purge Solenoid Control Circuit 

 Check for moisture in connections resulting in short, Damaged wiring from PCM to Solenoid,Faulty Purge Solenoid, Faulty PCM.

P0446 EVAP Vent System Performance 

 Check for Open/Short to vent valve control, Restriction/Blockage in vent valve,Faulty vent valve,Faulty PCM.

P0449  EVAP Canister Vent Solenoid Valve Control Circuit  

Fault in vent valve/solenoid circuit,Faulty connections or wiring,Faulty vent or purge solenoid,Fault EVAP vent solenoid,Charcoal canister saturated with fuel. 

P0453 Fuel Tank Pressure Sensor Circuit - High Voltage  

 Check for Open in Fuel Tank Pressure Sensor(FTP)signal wire,Faulty Ground to sensor,Faulty or Damaged connection or wiring,Short to Voltage in FTP Sensor,Faulty FTP Sensor.Too much pressure in tank check EVAP purge solenoid.

P0462 Fuel Level Sensor Circuit - Low Voltage 

Check for faulty connections or wiring,Short to ground. 

P0463 Fuel Level Senosr Circuit - High Voltage 

 Check for damage to fuel tank,Check for Open/Short to voltage,Faulty ground to tank,Check for Open in Fuel Level Resistor,Faulty Intrument Cluster.

P0500 Vehicle Speed Sensor Circuit

Usng DVOM-Check for Open/Short to Ground in Signal circuit,Faulty connections or wiring,Faulty VSS Sensor,Faulty TCM,Faulty PCM. 

P0560 System Voltage 

 Check ALL battery Connections,Check for Blown Fuses/Inline Fuses,Faulty Battery,Faulty Alternator,Faulty Voltage Regulator.

P0601 Control Module Read Only Memory (ROM) 

 Internal PCM Malfunction Replace PCM.

P0602  Control Module Not Programmed 

 Check for proper mating of connections at PCM,In some cases PCM can be Reflashed or Programmed,Replace PCM.

P0604 Control Module Random Access Memory (RAM) 

 Internal PCM Malfunction, Replace PCM.

P0606 Control Module Internal Performance  

 Internal PCM Malfunction, Replace PCM

P0620 Generator Performance 

 Check belt for slippage,Test for Open/Short in generator circuit,Faulty Battery or Charge,Faulty PCM controlled generator,Faulty PCM.

P0650 Malfunction Indictor Light (MIL) Control Circuit

 Test for Open/Short in MIL circuit,Faulty connections or wiring,Faulty MIL bulb,Faulty PCM.

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