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Unread 11-09-2015, 05:16 PM   #1
Twister1
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Location: Houston, TX, Texas
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P0300/306 code

Engine misfire, cyl 6 misfire
2012 Wrangler Sport, 30K miles, 6sp manual, almost no electronics/power except a radio.
The motor seems to be running fine, I don't feel or hear any misfires, and it idles smoothly. I'm thinking maybe a bad sensor somewhere. Any ideas?

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Unread 11-09-2015, 05:30 PM   #2
222Doc
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Sounds like a bad head issue, well known on 12-13's. You will need to take it in. they will clear it and wait too see if it fixes its self. SO DO NOT clear it your self. They may just repair it but most wait to see it happen again. Then they may do a leak down test. That will show if the issue is the valves. when it fails they replace the head.

Mine went out at 20K, ran fine too. Excepting at very high altitude i did notice it ran rough. above 9k.
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Unread 11-11-2015, 03:39 PM   #3
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Quote:
Originally Posted by Twister1 View Post
Engine misfire, cyl 6 misfire
2012 Wrangler Sport, 30K miles, 6sp manual, almost no electronics/power except a radio.
The motor seems to be running fine, I don't feel or hear any misfires, and it idles smoothly. I'm thinking maybe a bad sensor somewhere. Any ideas?
Hey Twister1,

TSB 18-007-12 may relate to your vehicle:

SUBJECT:
Flash: MIL Illumination P0441, P0300, P0301, P0302, P0303, P0304, P0305, P0306,
P0420, P0430, P0133, P0153, P0835
OVERVIEW:
This bulletin involves selectively erasing and reprogramming the Powertrain Control
Module (PCM) with new software.
MODELS:
2012 (JK) Wrangler
NOTE: This bulletin applies to vehicle equipped with a 3.6L engine (sales code ERB)
built before **January 24, 2012 (MDH 0124XX)**.
SYMPTOM/CONDITION:
The customer may experience a Malfunction Indicator Lamp (MIL) illumination. Upon
further investigation the Technician may find that any of the following Diagnostic Trouble
Codes (DTC's) have been set.
a. **P0441 - Evap Purge System Performance**
b. P0420 - Catalyst Efficiency (Bank 1)
c. P0430 - Catalyst Efficiency (Bank2)
d. P0133 - O2 Sensor 1/1 Slow Response
e. P0153 - O2 Sensor 2/1 Slow Response
f. P0300 - Multiple Cylinder Misfire
g. P0301 - Cylinder 1 Misfire
NUMBER: 18-007-12
GROUP: Vehicle Performance
DATE: February 07, 2012
h. P0302 - Cylinder 2 Misfire
i. P0303 - Cylinder 3 Misfire
j. P0304 - Cylinder 4 Misfire
k. P0305 - Cylinder 5 Misfire
l. P0306 - Cylinder 6 Misfire
m. P0835 - Clutch Pedal Switch "B" Circuit High Manual Transmission Vehicles Only
Updating the software will correct the conditions listed above.

Please let me know if you have any further questions.
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Unread 11-11-2015, 05:48 PM   #4
222Doc
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Location: Lake Havasu City, AZ
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Yea they did that to mine did squat. Mine was bought 10/2011 and the head was dead by midway in 13 when Jeep had to do something as it was effecting many. That was Fiat just trying to get it to go away with software. Bad valves are hard to cover in code........Look at the dates here you know then they were blaming everything under the sun to NOT cover this issue, but as the lots started filling up with 3.6's with bad heads the cat was loose...........

Then again maybe the OP is very lucky and its a spark pack or plug............or cough cough, bad code...
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Unread 11-12-2015, 09:57 AM   #5
Twister1
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The dealership agree to replace the head under warranty. They just asked where I had the code read! (auto parts) So unless there is some other hitch in the gitalong, I'm good. Bad thing is, they are supposed to call tomorrow or Monday to let me know -when- they can do the repair. So I may have to wait a while....
edit: took it to River Oaks Chrysler, etc in Houston, simply because they are a big dealer. Know nothing about them.
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Unread 11-19-2015, 02:43 PM   #6
Twister1
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Followup: Got my Jeep back today, MUCH sooner than I anticipated. Everything seems fine. Happy camper!
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Unread 11-19-2015, 05:36 PM   #7
222Doc
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Great news. back in saddle again...
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