I've been trying to troubleshoot this for a few days now. I installed a sub/amp a few days ago, and first try to start the car, it wouldn't start.
The lights come on, but it will not crank. Specifically, it says engine failure and start failure. It also says engine started, when it doesn't...
So my focus popped up 3 codes to be specific
PO300- multiple cylinder misfire
PO302- cylinder 2 misfire
PO316- engine misfire on startup first 1000 rev
I originally thought it was my spark plugs which helped but didn’t stop it. What do you guys think and do you think I have to take it in or can...