Below is the diagnostic information showing what causes different trouble codes on a 2000 Buick Regal with a 3.8L engine.
DIAGNOSTIC TROUBLE CODES:3.8L V6 VIN 1 Auto 1
3.8L V6 VIN 1 Auto
Trouble Code: P0101
Mass Air Flow (MAF) Sensor Performance
Possible Causes:
Check for the following conditions:
Skewed or stuck TP sensor. A malfunctioning TP sensor or TP sensor circuit can cause the PCM to incorrectly calculate the predicted mass air flow value. Observe the Throttle Angle displayed on the scan tool with the
Trouble Code: P0102
MAF Sensor Circuit Low Frequency
Possible Causes:
MAF sensor element hot wire contaminated or the sensor failed MAF sensor signal shorted to ground or ground circuit problem MAF sensor wiring routed close to ignition wires, generator, solenoids or electric motors PCM has failed
Trouble Code: P0103
MAF Sensor Circuit High Frequency
Possible Causes:
MAF sensor power circuit has a high resistance condition MAF sensor is contaminated, dirty or it has failed MAF sensor wiring routed too close to the Generator or to close to ignition wires (this causes a EMI/REFI high frequency signal) Water enters th
Trouble Code: P0107
MAP Sensor Circuit Low Input
Possible Causes:
MAP sensor signal circuit shorted to sensor ground MAP sensor power circuit open between the sensor and PCM MAP sensor is damaged or has failed PCM has failed
Trouble Code: P0108
MAP Sensor Circuit High Input
Possible Causes:
MAP sensor signal circuit is open or it is shorted to VREF MAP sensor ground circuit open between sensor and the PCM MAP sensor is damaged or has failed PCM has failed
Trouble Code: P0112
IAT Sensor Circuit Low Input
Possible Causes:
IAT sensor signal circuit is shorted to sensor or chassis ground IAT sensor is damaged or has failed (it may be shorted) PCM has failed
Trouble Code: P0113
IAT Sensor Circuit High Input
Possible Causes:
IAT sensor signal circuit is open between the sensor and PCM IAT sensor signal circuit is shorted to VREF or system power IAT sensor is damaged or has failed (it may be open) PCM has failed
Trouble Code: P0117
ECT Sensor Circuit Low Input
Possible Causes:
ECT sensor signal circuit shorted to sensor or chassis ground ECT sensor is damaged or has failed (it may be shorted) PCM has failed
Trouble Code: P0118
ECT Sensor Circuit High Input
Possible Causes:
ECT sensor signal circuit is open between the sensor and PCM ECT sensor signal circuit is shorted to VREF or system power ECT sensor is damaged or has failed (it may be open) PCM has failed
Trouble Code: P0121
TP Sensor Signal Range/Performance
Possible Causes:
TP sensor signal circuit open or shorted to ground (intermittent) TP sensor VREF circuit is open or shorted (intermittent fault) TP sensor is damaged or it failed (may be cracked or sticking) PCM has failed
Trouble Code: P0122
TP Sensor Circuit Low Input
Possible Causes:
TP sensor signal circuit is shorted to sensor ground TP sensor signal circuit is open (except 1996-1998 models) TP sensor VREF circuit is open between sensor and PCM TP sensor is damaged or it failed (it may be shorted) PCM is damaged or has failed
Trouble Code: P0123
TP Sensor Circuit High Input
Possible Causes:
TP sensor signal circuit is shorted to VREF or system power TP sensor ground circuit is open between the sensor and PCM TP sensor is damaged or it failed (it may be open) PCM is damaged or has failed
Trouble Code: P0125
ECT Excessive Time To Enter Closed Loop
Possible Causes:
Check the operation of the thermostat (it may be stuck open) Coolant level is too low, or the coolant mixture is incorrect ECT sensor signal circuit has a high resistance condition ECT sensor is damaged or it has failed
Trouble Code: P0128
Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature
Possible Causes:
DTC P0128 will set if the diagnostic does not pass within 25 minutes after start-up. If DTC P0128 does not reset, inspect the following items:
Cooling system — Coolant level. Thermostat operation — Refer to Thermostat Diagnosis in Engine Cooling
Trouble Code: P0131
HO2S-11 (Bank 1 Sensor 1) Circuit Low Input
Possible Causes:
Air leaks in the exhaust system, intake manifold, vacuum lines Engine misfire condition present (look for P0300 series codes) Fuel system too lean (possible low fuel pressure, water in fuel) HO2S signal circuit is shorted to the sensor or chassis groun
Trouble Code: P0132
HO2S-11 (Bank 1 Sensor 1) Circuit High Input
Possible Causes:
Fuel system is too rich (fuel pressure too high, fuel pressure regulator leaking, or one or more fuel injectors sticking/leaking) HO2S element is silicon, water or fuel contaminated HO2S signal tracking (water intrusion) in the connector causing a short
Trouble Code: P0133
HO2S-11 (Bank 1 Sensor 1) Slow Response
Possible Causes:
Exhaust leak present in the exhaust manifold or exhaust pipes Fuel system is too rich (fuel pressure too high, fuel pressure regulator leaking, or one or more fuel injectors sticking/leaking) HO2S element is silicon, water or fuel contaminated or it fai
Trouble Code: P0134
HO2S-11 (Bank 1 Sensor 1) Insufficient Activity
Possible Causes:
HO2S heater is damaged or has failed HO2S signal or ground circuit has a high resistance condition HO2S signal circuit is open or shorted to system power (B+) HO2S has failed (i.e., it is silicon, water or fuel contaminated) PCM has failed
Trouble Code: P0135
HO2S-11 (Bank 1 Sensor 1) Heater Circuit Malfunction
Possible Causes:
HO2S heater ground circuit is open or has high resistance HO2S heater power circuit is open (test O2S fuse in fuse block) HO2S heater element is damaged or has failed PCM has failed
Trouble Code: P0137
HO2S-12 (Bank 1 Sensor 2) Circuit Low Input
Possible Causes:
Air leaks in the exhaust system, intake manifold, vacuum lines Engine misfire condition present (look for P0300 series codes) Fuel system too lean (possible low fuel pressure, water in fuel) HO2S signal circuit is shorted to the sensor or chassis groun
Trouble Code: P0138
HO2S-12 (Bank 1 Sensor 2) Circuit High Input
Possible Causes:
Fuel system is too rich (fuel pressure too high, fuel pressure regulator leaking, or one or more fuel injectors sticking/leaking) HO2S element is silicon, water or fuel contaminated HO2S signal tracking (water intrusion) in the connector causing a short
Trouble Code: P0140
HO2S-12 (Bank 1 Sensor 2) Insufficient Activity
Possible Causes:
Exhaust leak present in the exhaust manifold or exhaust pipes HO2S signal or ground circuit has a high resistance condition HO2S element is silicon, water or fuel contaminated PCM has failed
Trouble Code: P0141
HO2S-12 (Bank 1 Sensor 2) Heater Circuit Malfunction
Possible Causes:
HO2S heater ground circuit is open or has high resistance HO2S heater power circuit is open (test O2 fuse in fuse block) HO2S heater element is damaged or has failed PCM has failed
Trouble Code: P0167
EVAP Purge Solenoid Control Circuit Malfunction
Possible Causes:
Purge solenoid control circuit is open, shorted to ground or shorted to power (B+) Purge solenoid power circuit is open (check ENG EMISS fuse) Purge solenoid is damaged, or the PCM has failed TSB 71-65-66 contains a repair procedure for this code
Trouble Code: P0171
Fuel Trim System Lean (Bank 1)
Possible Causes:
Air leaks in intake manifold, exhaust pipes or exhaust manifold Fuel control sensor is out of calibration (ECT, IAT or MAF) Low fuel pressure (fuel filter clogged, pressure regulator failure) One or more injectors restricted or pressure regulator has f
Trouble Code: P0172
Fuel Trim System Rich (Bank 1)
Possible Causes:
Base engine “mechanical” fault affecting one or more cylinders Excess fuel vapors in crankcase (the oil needs to be changed) EVAP system component has failed or canister fuel saturated Fuel control sensor is out of calibration (i.e., ECT, IAT or MAF)
Trouble Code: P0201
Fuel Injector 1 Control Circuit Malfunction
Possible Causes:
Injector 1 power circuit (B+) is open (check the power fuse) Injector 1 control circuit is open between injector and PCM Injector 1 control circuit is grounded between injector and PCM Injector 1 is damaged or it has failed PCM is damaged
Trouble Code: P0202
Fuel Injector 2 Control Circuit Malfunction
Possible Causes:
Injector 2 power circuit (B+) is open (check the power fuse) Injector 2 control circuit is open between injector and PCM Injector 2 control circuit is grounded between injector and PCM Injector 2 is damaged or it has failed PCM is damaged
Trouble Code: P0203
Fuel Injector 3 Control Circuit Malfunction
Possible Causes:
Injector 3 power circuit (B+) is open (check the power fuse) Injector 3 control circuit is open between injector and PCM Injector 3 control circuit is grounded between injector and PCM Injector 3 is damaged or it has failed PCM is damaged
Trouble Code: P0204
Fuel Injector 4 Control Circuit Malfunction
Possible Causes:
Injector 4 power circuit (B+) is open (check the power fuse) Injector 4 control circuit is open between injector and PCM Injector 4 control circuit is grounded between injector and PCM Injector 4 is damaged or it has failed PCM is damaged
Trouble Code: P0205
Fuel Injector 5 Control Circuit Malfunction
Possible Causes:
Injector 5 power circuit (B+) is open (check the power fuse) Injector 5 control circuit is open between injector and PCM Injector 5 control circuit is grounded between injector and PCM Injector 5 is damaged or it has failed PCM is damaged
Trouble Code: P0206
Fuel Injector 6 Control Circuit Malfunction
Possible Causes:
Injector 6 power circuit (B+) is open (check the power fuse) Injector 6 control circuit is open between injector and PCM Injector 6 control circuit is grounded between injector and PCM Injector 6 is damaged or it has failed PCM is damaged
Trouble Code: P0218
Transmission Fluid Over-Temperature (4T60-E, 4T65-E)
Possible Causes:
ATF is low, contaminated, burnt or dirty Engine cooling system has an airflow restriction Transmission cooling system has an airflow restriction Transmission cooler lines are bent, damaged or restricted Transmission internal failure (i.e., low line pr
Trouble Code: P0230
Fuel Pump Control Circuit Malfunction
Possible Causes:
Fuel pump relay power circuit is open (test B+ from fuse box) Fuel pump control circuit is open or shorted to ground Fuel pump control circuit is shorted to system power PCM has failed TSB 00-06-04-023 contains a repair procedure for this code
Trouble Code: P0243
Supercharger Boost Solenoid Control Circuit Malfunction
Possible Causes:
Boost solenoid circuit is open between the solenoid and PCM Boost solenoid circuit is shorted to ground Boost solenoid power circuit is open to system power Boost solenoid is damaged or has failed PCM has failed
Trouble Code: P0300
Multiple Engine Misfire Detected
Possible Causes:
Base engine mechanical fault that affects one or more cylinders Fuel metering fault (high fuel pressure or fuel contaminated) EVAP system problem or the EVAP canister is fuel saturated EGR valve is stuck open or the PCV system has a vacuum leak Igniti
Trouble Code: P0301
Cylinder 1 Misfire Detected
Possible Causes:
Air leak in the intake manifold, or in the EGR or PCV system Base engine mechanical fault that affects only Cylinder 1 Fuel delivery component fault that affects only Cylinder 1 (i.e., a contaminated, dirty or sticking fuel injector) Ignition system pr
Trouble Code: P0302
Cylinder 2 Misfire Detected
Possible Causes:
Air leak in the intake manifold, or in the EGR or PCV system Base engine mechanical fault that affects only Cylinder 2 Fuel delivery component fault that affects only Cylinder 2 (i.e., a contaminated, dirty or sticking fuel injector) Ignition system pr
Trouble Code: P0303
Cylinder 3 Misfire Detected
Possible Causes:
Air leak in the intake manifold, or in the EGR or PCV system Base engine mechanical fault that affects only Cylinder 3 Fuel delivery component fault that affects only Cylinder 3 (i.e., a contaminated, dirty or sticking fuel injector) Ignition system pr
Trouble Code: P0304
Cylinder 4 Misfire Detected
Possible Causes:
Air leak in the intake manifold, or in the EGR or PCV system Base engine mechanical fault that affects only Cylinder 4 Fuel delivery component fault that affects only Cylinder 4 (i.e., a contaminated, dirty or sticking fuel injector) Ignition system pr