TSB : Code 45 - Rich Exhaust Indication

Details

Code 45 indicates the ECM has seen: High oxygen sensor voltage. More than specified time (about 2 minutes). Above a specified TPS value. Closed loop. A high voltage can be caused by a rich exhaust or an O2 sensor contaminated with silicone. NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s). On 1987 5.7L (VIN 6) B Body, dwell less than 45 degrees indicates that engine should be checked for cause of intermittent rich condition; purge or bowl vent valves leaking, fuel in crankcase, fuel in evaporative canister, or sticking mixture control solenoid or metering rods. On all others, dwell less than 50 degrees indicates that engine should be checked for cause of intermittent rich condition; purge or bowl vent valves leaking, fuel in crankcase, fuel in evaporative canister, or sticking mixture control solenoid or metering rods. This step tests ECM response to a lean engine condition. A drop in dwell indicates that ECM and O2 sensor are not faulty. This step tests ECM response to a lean O2 signal (low voltage). If there is no dwell change with a grounded lead to O2 sensor terminal "9", fault is in ECM. Open O2 sensor wire would have set Code 13. This step checks voltage from ECM at O2 sensor harness. Normal voltage at this point is ECM bias voltage for no O2 signal, approximately .45 volt. If voltage is high, wire to ECM could be shorted to battery voltage, or ECM is faulty. Fig 1: Code 45 - Rich Exhaust Indication Flow Chart Fig 2: Code 45 - Rich Exhaust Indication Flow Chart