Quote:
Originally Posted by blue62
Your assumptions are incorrect 
Ignition coils can fail totally or they can exhibit intermittent failure.
They can also exhibit weak spark and never miss or fail.
Also there is no CEL (OBDII) code for ignition coils.
There are codes for misfires, but misfires can be caused by many factors not just coil issues. |
Yes you're right, you don't get a code for a coil being bad, but you do get a code for a miss fire, and 99% of the time it's a bad plug or a bad coil. So it's very simple to figure out if you have a bad coil or a bad plug. Let's say you get a code for cylinder #4 for example, all you have to do is change a coil from a different cylinder to #4 and you will know if you have a bad coil or a bad plug. If the code comes back to cylinder #4 you know you have a bad plug, but if the code comes back to the cylinder that you changed the coil to, you know it's a bad coil
