Diagnostic Strategy: Diagnostics

WARNING: This page is about a different car, the 2003 Mercury Marauder, 2003 Mercury Grand Marquis, and 2003 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

Carry out on-board diagnostic procedures key on engine off (KOEO) and key on engine running (KOER).
Record all diagnostic trouble codes (DTCs).
Repair all non-transmission codes first.
Repair all transmission codes second.
Erase all continuous codes and attempt to repeat them.
Repair all continuous codes.
If only pass codes are obtained, refer to DIAGNOSIS BY SYMPTOM for further information and diagnosis.

Follow the diagnostic sequence to diagnose and repair the concern the first time.