They will pull the codes for you for free at AutoZone. Just because the light is not on does not mean you don't have some stored codes in there. But, if it is intermittent CPU problems, the code that appears may not be the problem, just a symptom of the CPU dying. I'd start with the codes, though. Good luck with this one.
1999 Ford Expedition XLT 4.6L
2003 Volvo S80 2.9L |