If the fault has been corrected (hopefully) does the light go out after a period or does it always need to be reset?

Jonathan

 

I think it needs to be reset each time. The problem remains if it comes on again shortly after resetting. I could be wrong though.

 

Yep, as above.

Just pull the ECU backup fuse out for a couple of mins (or remove battery terminal), then plug it back in.

All gone

 

For some codes the light will go out after several driving cycles, but I think the code would still remain in the ECU.

Best bet would be to get the code number before resetting anything, readers can be had off Ebay very cheaply.

 

I had a CEL pop up last week and it cleared itself after a fair bit of driving. I totally agree with the others tho, definately get the code read before resetting anything because you never know how serious the fault could be.

 

Thanks for the replies.

Car was serviced, but on the way to the garage it wouldn't idle properly, though the CEL had come on a couple of days prior to that.

They said it was misfiring on 2 3 and 4.

Took it back and they changed the plugs but when I got the car back the CEL was still on, hence my question.

Have to say I'm still not confident as the idle is not right. I reset the light and am going to drive it up the D road to Crewe for the afternoon. We'll see what happens.

 

It depends why it came on.

Some are a "something major has gone on, I'll keep telling you", others are "whoops, bit of a blip there, but now it's fine I'll turn the light off".

 

I would by a CEL reader, you need to be very carefull with these codes!!

 

Or dig out the laptop and fire up AEM Pro .. then get scared with all the pretty grids that can break your car.

I've had loads of CEL lights on the S.

Thinks like actual sensor issues tend to go after time (MAP, ABS, o2) .. errors sensors pickup tend to stay (Missfires).