2015 jku cyl six misfire code

nightfirem10

nightfirem10

New member
So, I have a check engine light keeps coming on when my jeep goes over 5000 rpm,had the dealer check it out. They told me it requires more diag time (6-8 hrs swapping parts to see if it follows) has anyone had same such issues? And on that note don't you think they should have just thrown a spark plug at it as the most basic fix for a mis-fire?
 
utiadam

utiadam

LOSER
How many miles do you have? Chances of it being a spark plug are pretty slim or it would be a constant misfire and not above a certain rpm. Could be a coil, ECU flash, faulty ECU, maybe a damaged flywheel??
 
crowrb29

crowrb29

New member
If it's p306 it might be a bigger problem. I had it happen to my 13 and it was a big issue for the 12s. It ended up getting fixed under warranty. Some of the pentastars had bad cylinder heads and they have since changed the design. FWIW, I haven't had any issues in the 24,000 miles since its been fixed.
 
nightfirem10

nightfirem10

New member
It's got about 1600 miles on it, only codes on high rpm. The last time the light stayed on until the dealership cleared it?
 
crowrb29

crowrb29

New member
That's what initially prompted mine. I'd clear the code, then it would pop back on about a week later. Eventually it just decided to stay on. I went through a month long process with the dealership trying to get it fixed.
 
utiadam

utiadam

LOSER
Does it flash when it comes on or just turn on? Do you know if it's only under load or if you could rev it at a stop and trigger it?
 
nightfirem10

nightfirem10

New member
Utiadam, it would flash some times, also come on for a bit then go out by itself. I never tried to trigger the light stationary. First time it did it was just after I got it and went out wheeling. This last time, I pulled out to pass a guy on the highway. Both under load and higher revs.
 
utiadam

utiadam

LOSER
nightfirem10 said:
Utiadam, it would flash some times, also come on for a bit then go out by itself. I never tried to trigger the light stationary. First time it did it was just after I got it and went out wheeling. This last time, I pulled out to pass a guy on the highway. Both under load and higher revs.
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When it flashes it means the misfire is currently happening. I'm just trying to figure out how hard it will be for the tech to reproduce the problem. I'm a tech but for Mercedes Benz not jeep. Sometimes we get cars in that have stored misfire codes that only happenb on cold starts which are usually fixed by a flash. Something like you're explaining would probably need further diag time like they said.
 
crippledpetey

crippledpetey

-
I've had this issue and more. In fact my jeep is at the dealer for a third time. I've had cylinder 4 and 6 done. If you're under warranty let them have the headache. The misfire could be from a cam shaft position sensor, coil, plug, or just an electrical issue that's confusing the motor. I've been dealing with this a lot recently.

Sorry to hear you're having the problem.
 
Remlap

Remlap

New member
I had started a thread on this exact problem a while back, we have a 14' with identical code (P0306) and same symptoms.

Coils swapped, same code
Head replaced, same code
Camshaft replaced, same code
PCM replaced, same code + a P0520 code (I think - oil pressure sensor)

Engine is being replaced next week...

The way I could always duplicate the problem was to run it at a steady 4,500 rpm in either 2nd or 3rd gear, it will flash first few seconds but eventually go on steady to produce the code. Otherwise, just hit a 5 or 6% grade somewhere and try to go the speed limit.

Anyway, sounds like they have some more issues to deal with.
 
671JKU

671JKU

New member
Holy shit are you serious?! Was there ever a recall for this defective design or something? Thanks.
 
Remlap

Remlap

New member
Not that I know of, but this seems like a hell of a coincidence as several people just on here have identical problems.

Hope I don't get a new engine with the same shit, since the 15's have it too ha-ha.
 
nightfirem10

nightfirem10

New member
Doesn't make me happy to hear what everyone has had, I will let you all tomorrow after I hopefully get it back from the dealer....
 
sipafz

sipafz

Caught the Bug
Since you are not getting anywhere with the dealership, why don't you try and isolate the problem yourself by swapping the ignition coils since that is an easy first step?
 
M

maldoror

New member
Remlap said:
Just an update if anyone is interested, new motor fixed ours.
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My 2013 JK is currently in the shop with this exact same behavior. The third time I've had to take it in for this issue, but at least I've got the tech to replicate the P0306/CEL at 4700 RPM issue. They've already done lifters. We'll see what they throw at it before replacing the engine :\
 
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