The Nissan Altima is a mid-size automobile manufactured by Nissan, and is arguably a continuation of the Nissan Bluebird line, which began in 1957.

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What could be causing a cylinder to misfire? code 0306

When starting my 2003 3.5 altima, it runs very hard. the whole front end was vibrating. As i continued to drive the "service engine soon," light began flashing, but then went away. After driving for about a mile, my car was driving normal. When i got home i manually got the code by putting the EMC in diagnostic mode, i came up with 0306, which appears to be misfiring in cylinder six. What could be causing the cylinder to misfire? How should i go about fixing it?

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jxclusive12, this could be caused by bad exhaust valves, bad MAP sensor, bad crankshaft and/or camshaft position sensor, bad ignition coils as well as bad spark plugs, bad injectors. Of course,last but not least, this could be a bad PCM.Try to repalce the spark plugs first, then the coil pack. also vhange injector #6 with #4 and see if that makes a difference.

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Thanks for the help. I started with changing the spark plugs, which happens to be the biggest pain in the ^*& for the rear three plugs anyhow. What i noticed was when i pulled out the ignition coil on the right back plug, it was drenched in oil. Im assuming this is what is causing that cylinder to misfire. Any possible ideas on what this can be? and how to go about fixing it?


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Code 0306 means that cylinder # 6 is missing...since that one is drenched in oil, that is probably the problem. Most likely cause for the oil is a leaky valve cover gasket. I've heard that a few people had issues with the valve cover itself causing the leak, so check it closely when you pull it to replace the gasket.

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I had the same problem. I replaced the coil pack and spark plug on the misfiring cylinder and she runs great.. I was told by Dealership the engine was completely finished.. obviously untrue.. they also keep calling me with "deals on a new Nissan"... I am quite happy with my car despite having almost 400 000 kms on the engine!

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