Cadillac Repair: 1990 cadilallac Brougham, service engine soon light, cadilllac, code scanner

Question
I have a 1990 Cadilllac Brougham rear wheel drive with the 5.7 engine with  fuel injection. When I first start and drive the car no service light problem.  After I drive the car about 3 to 5 miles the ( service engine soon light ) comes on. The car still runs fine and does not seem to bother performance of car. Any suggestions on what to check?   Thanks

Answer
Hello,

This is an emissions problem and no, your engine is not running to full efficiency. This light is a symptom and until diagnosed with a code scanner (available at parts stores), the problem will not be known. The light comes on to store a trouble code with the computer system. Just because that light is not on all the time does not mean there are not codes stored.

In fact, if the light stays on, that tells you it is a hard code and something needs fixed right now.

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Thanks,

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