Volvo Repair: 740 Check engine light, failure code, volvo 740

Question
The check engine light on my 1992 Volvo 740 (no turbo) wagon goes
on intermittantly.  Sometimes it seems like it goes on after warm
up, sometimes it's on first thing in the morning.  It will go off
without any specific action throughout the day and come back
on the same way.  My mechanic says not to worry about it- car
runs fine, temp is good, oil and oil pressure are good, etc.

Is there a finite amount of things this light refers to?  Is there a
list?  Can I reset it when it goes on?  Any advice?

Thanks,

Tim Perry

Answer
Hi Tim,

        A Check engine light can go either way...VERY EASILY.
      If you're guessing...you run the risk of dusting off the engine...overheating...electrical problem(700 series have a less than great electricals)...or an oil failure...
         Some of the items that trigger the check engine light are minor too...failed electrical connection ...failed  sensors....
    My guess is that you have faith in your mechanic's opinion.
     If he had a hand held computer it would list failure code...expensive software.

   Bilbo