Would bad coil always cause ck engine light?
 

I have a 98 ES 300. I was driving home the other day and it started to miss a little. When I got home I popped the hood and could sorta hear an arcing sound from the front of the engine. I cut it off and started it again and it was fine and have driven it a lot today and it is fine.

Question is: If I have a bad coil would it always throw a code?

Myself, I think it may be one of the coil boots.....but I cannot tell until it starts to do it again!

thanks in advance!

It should make the check engine light come on. Maybe your car is storing the code in the ECU. You can have it checked somewhere for free like autozone or something. Don't bring it to the dealer.

Maybe the heat makes it act up because whenever it got hot outside the main relay in my Acura stopped working therefore killing my engine. I resoldered it and fixed that problem though.

Was it really hot out when your car was starting to miss?

I am not sure exactly what it is but I'm trying to help you out anyway.

I had it checked and there are no codes stored. Irritating as heck......it starts doing it and i rush home to unplug a coil to see which it is and it starts running right again....guess I just have to wait until it does it all the time.

thanks