Diagnostic Aids

Code 45 or rich exhaust is most likely caused by improper fuel pressure, HEI shielding, canister purge, MAP sensor, TPS, O2 sensor contamination or EGR system. If code is intermittent, see TESTS W/O CODES article. On VIN 6, if O2 sensor heater fails, a Code 44 or Code 45 may set. To diagnose heater part of O2 sensor, refer to I - SYS/COMP TESTS article.

Fig 1: Code 45 (VIN 5) Circuit Diagram

Fig 2: Code 45 (VIN 6) Circuit Diagram

Fig 3: Code 45 Flow Chart