Ford Repair: engine lights, apparent reason, emissions

Question
when the check engine light comes on with no apparent reason the car is a 1992 mercury grand marqui there had been no major repairs

Answer
The Check Engine Light comes on when there is a problem in the Emissions System. The system will have to be scanned again for Diagnostic Trouble Codes (DTC's). The code will indicate where the computer sees the problem. The code doesn't always mean that the sensor is bad, it could also be a wiring problem, or a symptom of a different problem.

I hope this helps,
Dave