Diagnostic Aids

Check for poor connection at PCM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal connection. If connections and harness appear okay, observe front HO2S display on scan tool while moving all related harnesses and connectors. A change in scan tool display indicates fault location. Check front HO2S heater operation. If DTC cannot be duplicated, check scan tool FAILURE RECORDS to determine mileage since last DTC was set.