2000 Buick Regal 3.8L Trouble Codes

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