I've got a 2012 1.8 Chevrolet Sonic with a misfire. I've checked the injectors, compression and all is okay, but the coil is the one unit that sits on top of the motor. How do I test that?
Unfortunately, for this problem GM has a poor design. The entire coil unplugged is a whole assembly and you really can’t check that thing individually because it has a sealed unit that goes on top. My advice is to have a guy like me or YourMechanic to come to you and diagnose your misfire.
They can analyze your computer system with their dealer-level scanners and if they find that you have various misfires then you just have to buy a new coil pack. You can get one that is not that expensive from an aftermarket seller. They do seem to go out a lot on this particular vehicle and you really can’t check them yourself. You need a mechanic with fancy scan tools to see if they are okay, or get a replacement coil pack.