My check engine light came on. I had it checked and the diagnostic said it was a misfire. The mechanic couldnt figure out why. So he reset it to see if it would come back. About a week later it did.

The car is running fine. No sputtering or hiccups or anything like that.

The second time it came back on was right after I filled up with gas. I use 87 octane. Could that have anything to do with it or just a coincidence?

Anyone have any clue as to what's going on?

Thanks!

 

The car requires premium gas, 89 is the recommended minimum so yeah, that might be the cause. Doesn't seem to like ethonol either.

 

The check engine light went out on it's own today. Could this be electrical? I didnt think those lights ever went off without being reset by a mechanic.

 

Don't most/all OBDII vehicles turn off the CEL after three run cycles without the fault??

 

the different codes have different priority, and severity. some reset never, some after one start some after a few starts, and some have complicated scenarios before they might go off.

There is no real reason to suspect that the light is for the same reason each time. The only way to know why the light was on is to read the code. If the light went out, the code will still be stored in memory.

is there not a fairly BOLD sticker on the gas filler door that says USE PREMIUM UNLEADED ONLY ??????????

 

Yeah..of course..but sometimes I cant afford to fill up with the good stuff. Times are tough ya know.

Thanks for the help. I'll have the code read when I get my brakes done. See if it says anything other then misfire.