Code 45 - Rich Exhaust Indication
Code 45 indicates ECM has seen:
- Oxygen sensor voltage greater than .7 volt.
- More than specified time (about 30 seconds).
- Throttle angle between 3-45 percent.
- Closed loop.
- Time since engine start is more than one minute.
A high voltage can be caused by a rich exhaust or an O2 sensor contaminated with silicone.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- 1) On 1987-1988 5.0L (VIN G/H) and 5.7L (VIN 6) B & F 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.
- 2) This step tests ECM response to a lean engine condition. A drop in dwell indicates that ECM and O2 sensor are not faulty.
- 3) 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 No. 9, fault is in ECM. Open O2 sensor circuit would have set Code 13.
- 4) 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, circuit No. 412 to ECM could be shorted to battery voltage, or ECM is faulty.
- 5) See INTERMITTENTS in TROUBLE SHOOTING section of article.