Q: Rough idle/Check Engine light/Cylinder # 2 misfre

asked by on December 20, 2016

Rough idle and check engine light came on. I had the code read (P0302 code - cylinder #2 misfire). I have replaced the #2 coil and driven it about 15 miles or so since - but still have the rough idle. Is there a chance this clears up as a result of the replacement? What are other likely causes - spark plug? Clogged fuel injection perhaps? Basically, I want to find out the most likely cause. Also, I want to check and make certain that I'm not risking some sort of extreme engine damage by driving over the next couple of weeks until I have the time to get it serviced.

My car has 235000 miles.
My car has an automatic transmission.

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Hello, thank you for writing in. The spark plugs may absolutely be the cause of your misfire. Even if only one cylinder is registering a misfire at this time, you should replace all of them at the same time. The spark plugs can be replaced every day and it would only improve your engine performance.They are the most likely component to cause these issues, as they are used so frequently and aggressively. Any part that works that hard is going to need extra attention. If you replace your spark plugs, and the issue continues, you can turn your attention to the fuel system. Additives can be mixed with the fuel to help clean the fuel injectors of any build up. Keep in mind the engine will burn the deposits that are broken free from the system and you may feel it when driving. It should be short lived and not cause any issues. Start by replacing your spark plugs, and take any further diagnosis from there.

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