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P0302, P0304 and P0306 at the same time

4.1K views 6 replies 7 participants last post by  JeepinMass  
#1 ·
My 2013 seems to run just fine but just got these codes today. I replaced the spark plugs just 10k miles and have a clean air filter. I bought it used 2 years ago and would appreciate any advice here. Thanks in advance!
 
#2 ·
Welcome to the Forum, from Cave Creek AZ,
Possible bad cylinder head. Next step is have a compression test on them cylinders. I suggest that you take it into your Dealer, and have it diagnosed.
 
#3 ·
Is it running rough at idle? If you clear the faults, do they come back right away? If yes to both, then I agree with Old Dogger. If not, sometimes multiple misfire faults are logged when only one cylinder has an issue. Your scanner may be able to display number of misfires logged per cylinder. If one cylinder has significantly more misfires than the rest, you can try swapping coils easily to see if the issue follows the coil. If not, you can try the same with spark plugs.
 
#6 ·
When i see those codes my immediate reaction is bad cylinder head.
 
owns 2004 Jeep TJ Rubicon