I finally bought a car, thanks for all the helpful suggestions on the forums here.
It’s a 99 Mazda Protege with 142k miles.
On the first big drive (80 miles round trip), the check engine light came on.
The manual says it could be a whole of things, but might be that a fuse was burnt out. So I replace the fuse and the light goes out (yeah!), but then I put back the original fuse and the light is still off. So now I’m confused. What caused the light to go on?
Should I still take it to a mechanic (I have already taken it once, before this, for a general diagnostic, he fixed a brake problem but found nothing else) or should I just drive it and assume that nothing is wrong as long as the light doesn’t come on again ?
the light comes on when a sensor is out of range.take it to autozone and they can check the code.it could be something as simple as a loose gas cap .the code they pull will tell where the problem is.it wont pin point the problem but it will tell you which system it is and you can begin testing or checking there.most codes that i have checked at work are mostly emissions(small leak) which is usually a gas cap that was put back on tight.
Bring the trouble code here; and bring that quote that says it might be caused by a fuse. I have never heard that definition of a DTC (Diagnostic Trouble Code).
That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here.
Regarding warning lights:
if the coolant temp light comes on, shut off the engine ASAP
if the oil warning light comes on, shut off the engine ASAP
if a FLASHING MIL/CEL comes on, shut off the engine ASAP
ASAP means driving to the berm of the highway right now and not waiting for the next exit.
But if the MIL/CEL is not flashing, then it’s not an urgent indicator.
I called Autozone about checking the codes. Apparently none of the Autozones in California offer that service.