I started getting P0302 after a month or so since I replaced all 4 spark plugs.....I bought some cheaper brand from Advanced Auto. I also need to get the car inspected and CEL will fail me. My question is can new spark plug cause P0302 misfire code?
I think recently @plain OM said that he did not believe subaru used the P0300 generic code in any cars.P0300 is a generic misfire code. P0302 means the cam/crank sensor rotational velocity measurement zeroed in on Cylinder #2 as the source of instability. It could be a bad plug, fouling of that plug, a bad wire, or a bad coil pack, partially clogged injector, a valve seal issues, etc.
Before you go crazy, start with the basics. Observe your running engine on a damp, dark night. When I was getting a misfire code, I could actually 'see' a corona glow from leakage at the wire boot to coil pack junction. Remove the wire from the coil pack and inspect both sides for any metal discoloration or carbon tracks. Cleaning it up 'fixed' it temporarily, but it would return every month or so. Eventually I just replaced the wires and coil pack.
I did not notice anything unusualDid you inspect the boots (spark plug and coil end) for hardness, cracks, carbon tracks? How do the silver connector ends look? How about the coil conductors? Was there anything odd about the plug you pulled out?
Remember that this could also be a fuel or air issue.
yes,I reset CEL. After 133 miles of driving, CEL came back.
Right now my concern is to pass state inspection. Do you think the inspection will somehow see reset CEL?