Every trip or two of over forty or so miles will inevitably cause the Check Engine light to illuminate on my N/A '96 850, which is otherwise very well-maintained and drives flawlessly. The code reader not only states "no codes" but when I check the status of the MIL it says that the light is off, even with it glowing away right in front of me. Running the process to turn the light off does in fact turn it off. But before long the light goes on and the process repeats itself. This has happened maybe six times in the last few months (I don't drive a lot--I take a commuter train to work).

In this and other forums this issue has come up a few times, almost always with newer, more computer-laden models. Some think it may be Volvo-specific codes, which I suppose is possible, but I thought that the Check Engine light was pretty much restricted to emissions items and not used for codes about power windows or door locks.

Any guesses, folks? Or better, has anyone got anything definitive? It's got me stumped...

Thanks!