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P0306 Cylinder 6 Misfire Code - 2018 JLU

dpereira

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This morning CEL came on for the fist time in 58k miles, whole jeep was shaking on the highway and also when parked.
scanner is showing code P0306, cylinder 6 misfire.

2 weeks ago I installed K&N intake, not sure if this could have been the cause but I have not had any issues until now.
my thought was to put back stock intake over the weekend and clear the code to see if anything changes.

any suggestions on what to do or what it could be? has anyone else had this issue with CAI?
Hoping someone can point me in the right direction before I have to waste time at the dealer.

thanks in advance
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JimLee

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A CAI wouldn't cause just one cylinder to misfire. This is one of the codes I had when I had a valve cover leaking directly onto the connector of the passenger side O2 sensor, but I also had several other codes pointing to a bad O2 sensor.
 

mwilk012

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Cracked/fouled spark plug, bad ignition coil, bad fuel injector, damaged camshaft/rocker arm/lifter, bad PCM...

a mouse or other rodent

Water ingress to wiring harness

these are just a few possibilities.
 
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dpereira

dpereira

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i cleared the code and everything was fine over the weekend, yesterday morning it came back but jeep wasnt shaking like previously. i cleared it again and again the engine sounded normal.

wondering if the computer could be causing it to misfire?
if/when it happens again i will bring it to the shop.
 

HeavyUser

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i cleared the code and everything was fine over the weekend, yesterday morning it came back but jeep wasnt shaking like previously. i cleared it again and again the engine sounded normal.

wondering if the computer could be causing it to misfire?
if/when it happens again i will bring it to the shop.
Put the original intake back on, if it happens again then take it to the dealer and get it fixed?
 

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mwilk012

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i cleared the code and everything was fine over the weekend, yesterday morning it came back but jeep wasnt shaking like previously. i cleared it again and again the engine sounded normal.

wondering if the computer could be causing it to misfire?
if/when it happens again i will bring it to the shop.
clearing codes never fixes anything and does delete important diagnostic data. Yes, a failed pcm can cause a single cylinder misfire.

unless you unplugged something and didn’t plug it back in right, there is no way the air intake is the cause of the problem.
 

tlzfjr

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Had the same problem with our '21 GC Trailhawk at just over 1k miles. Turned out to be a bad spark plug. Haven't had an issue since and am now at 10k.
 

AlgUSF

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I would start easy and move to hard. Check the spark plug, if it isn't a spark plug, swap an ignition coil with another cylinder. There are a lot of permutations of issues, and certainly cover the easy ones before you go to the stealership dealership.
 

mwilk012

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Left bank, all the way at the rear. Don’t leave us hanging, OP.
 
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dpereira

dpereira

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everything has been fine the since Monday, im waiting for the CEL to come back then i will drop it off at my local shop to have them check the spark plug/ignition coil.

i will post the outcome once i find out what it was
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