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Old 09-02-2014, 04:08 PM   #1
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2012 JK Wrangler Sport error code P306

HELP! I have a check engine light on currently, and the OBD2 code reads P306, what is the code referring to??

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Old 09-02-2014, 04:18 PM   #2
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P0306 is a cylinder misfire.

Since you've got a '12, you might have a bad cylinder head....

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Old 09-02-2014, 04:22 PM   #3
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I don't mean to come off rude or anything; where are you getting your information?
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Old 09-02-2014, 04:26 PM   #4
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The thread right below yours is a good place to review info. about this issue. Code P0306
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Old 09-02-2014, 04:27 PM   #5
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Thank you
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Old 09-02-2014, 04:30 PM   #6
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You almost certainly need a new cylinder head. There was a design flaw in the left cylinder head (2,4,6 bank), which leads to misfires. Only option is a full replacement head. The warranty was extended to 10y/150k. Bring it in.
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Old 09-02-2014, 04:45 PM   #7
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The light came on last night while i was on the surface streets in my town. When I checked the code with the OBD2 this morning, it came up at the p0306. After the engine was started up again, the engine light went away, and after a quick test drive around the block, and after a few times restarting the engine, no engine light has come on again.

the only recent engine work that has been done, if you can even call it that, was new coils that were put in Friday last week. Other than that, all parts of the engine haven't been messed with.

As stated it is a 2012 Wrangler Sport with about 19500 miles.
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Old 09-02-2014, 04:54 PM   #8
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Quote:
Originally Posted by b1gr3d16 View Post
The light came on last night while i was on the surface streets in my town. When I checked the code with the OBD2 this morning, it came up at the p0306. After the engine was started up again, the engine light went away, and after a quick test drive around the block, and after a few times restarting the engine, no engine light has come on again.

the only recent engine work that has been done, if you can even call it that, was new coils that were put in Friday last week. Other than that, all parts of the engine haven't been messed with.

As stated it is a 2012 Wrangler Sport with about 19500 miles.
Why did they put new coils on it? Ticking noise? Running rough? Low MPG? Those are all symptoms of the bad head.
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Old 09-02-2014, 05:01 PM   #9
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Im the test vehicle for this performance shop i used to work at. The coils are supposed to increase the mileage, and maybe a little HP. I had been using a single coil of the testers for about 2 months, with an increase in 2 MPG.
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Old 09-02-2014, 05:07 PM   #10
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Im the test vehicle for this performance shop i used to work at. The coils are supposed to increase the mileage, and maybe a little HP. I had been using a single coil of the testers for about 2 months, with an increase in 2 MPG.
Honestly, I would remove those coils and put the stock ones back on. You don't want to be a test mule when your warranty is at stake. I doubt they would cover the head if they found those.
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Old 09-02-2014, 06:57 PM   #11
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That's very true. I will do that. Thank you for all the info and advice, it's very much appreciated!
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Old 09-02-2014, 07:51 PM   #12
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Yep..

Cylinder misfire, replace coils with stock and take it in for a head replacement.

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