Grand Marquis - check engine display light - Ford Forums

hively · 08-25-2004, 13:05

1994 Grand Marquis, 99,900 miles - good reliable vehicle. "Check engine" dash display light has just begun to come on as vehicle exceeds 60-65 mph. Must shut off engine to clear "check engine light." All fluids have been checked and are OK. Air intake is clear. I installed new air filter. Short of a visit to service tech, what else should I check? Air sensor? Any suggestions welcome.

taco_90 · 08-25-2004, 19:16

Had a GMC 1/2ton do that to me. If you can...do a code scan and see what comes up. For me it turned out to be the knock sensor. If you have a timing light then it's real easy to check. With the engine running and while using the timing light, tap on the intake manifold and watch to see if the timing advances. The knock sensor is designed to advance your timing if it detects a ping from the pistons. If there is no responce from the sender then it will set off the light on the dash.