The dreaded P0300 after warranty runs out

Mando

Mando

Member
Wave everyone!

After 6 years with my Rubicon JKU (2012 - Special ordered 08/2011 and received 11/2011), I've got the engine check light on and a P0306 code came up.

Jeep runs well. It's been about 6 months with the check engine on, and last week it blinked and engine started running rough. I was like 3 blocks from home, so got home and stopped and restarted the engine and the check light was back to solid and roughness was gone. Four days later, and Jeep still runs OK.

Needless to say, it is time to address this and wonder if worth taking it to the dealer. I'm out of warranty, but it's been discussed that there is a TSB on engine misfire which is potentially my problem and which extends the warranty further (or so I read on this bulletin)

I have a trusted good mechanic who can diagnose and hopefully fix this problem, but is it worth taking it to the dealer and risk paying dealer price (should they find that the problem is not part of any TSB or that such TSB does not exist)? or simply wouldn't cover as it's out of warranty?

What do you guys think on my dilemma?

Cheers!
 
I would definitely take it to the dealer. That way the code and symptom are documented. If they diagnose it as something else, you'll only have to pay for their diag fee. But if it is the cylinder head that has failed and it's covered under the extended program, then they can take care of it for you.
 
Thanks mate! Makes sense.

Is the diagnosis fee a flat fee? My understanding is that diagnosing a problem with a cylinder head requires several tests.

Is it common practice for a dealer to inform the client that there exist a TSB and that repairs are covered? Or would I expect them to try to hide it and charge me?

I obviously never took my Jeep for repair to the dealer and the only time I did for an oil change, they left the filter cap loose.

Thanks again for the reply!

Mando.-
 
Mando said:
Thanks mate! Makes sense.

Is the diagnosis fee a flat fee? My understanding is that diagnosing a problem with a cylinder head requires several tests.

Is it common practice for a dealer to inform the client that there exist a TSB and that repairs are covered? Or would I expect them to try to hide it and charge me?

I obviously never took my Jeep for repair to the dealer and the only time I did for an oil change, they left the filter cap loose.

Thanks again for the reply!

Mando.-
Click to expand...

Friend is having this problem at the moment, I believe he's at about $1,200 in diagnostics to tell him it is not under warranty because he wasn't doing services at a dealer.
I'd probably call and talk to them before letting them take a look personally. They did mention there was a TSB, but claimed the damage was caused by the above.
 
Exactly what I'm afraid of ... to get to the bottom of the problem requires hours $$$ of diagnosis (beyond the initial flat fee), and then they could play hard ball because I did the oil change myself.

Either way, won't be cheap, but I'm sure I'll be saving no less than 40% going elsewhere.

Thanks for the reply!

Mando.-
 
MTG said:
I thought they extended the warranty for this issue?


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Click to expand...

They did, but in our experience so far at least you have to pay for the diagnostic and if it's determined to be covered under TSB you are reimbursed.
If it isn't, you don't get your money back. It's bullshit really.
 
Mando said:
Wave everyone!

After 6 years with my Rubicon JKU (2012 - Special ordered 08/2011 and received 11/2011), I've got the engine check light on and a P0306 code came up.

Jeep runs well. It's been about 6 months with the check engine on, and last week it blinked and engine started running rough. I was like 3 blocks from home, so got home and stopped and restarted the engine and the check light was back to solid and roughness was gone. Four days later, and Jeep still runs OK.

Needless to say, it is time to address this and wonder if worth taking it to the dealer. I'm out of warranty, but it's been discussed that there is a TSB on engine misfire which is potentially my problem and which extends the warranty further (or so I read on this bulletin)

I have a trusted good mechanic who can diagnose and hopefully fix this problem, but is it worth taking it to the dealer and risk paying dealer price (should they find that the problem is not part of any TSB or that such TSB does not exist)? or simply wouldn't cover as it's out of warranty?

What do you guys think on my dilemma?

Cheers!
Click to expand...

P0306 cylinder 6 misfire.

Clear the codes then pull the #6 plug and swap it with #2.

Start it up and wait for the code - if it changes to P0302 change all your plugs.

I went thru that 3 weeks ago. Pulled the plug and it looked perfectly normal.

Swapped it and the error code followed the plug. Changed out all the plugs no more issues.

Cheap investment in time and easy troubleshooting.

If the 3.6 is the same as the 3.8, the plugs are on the easy access side of the engine block
 
Just had this problem a few weeks ago. Check your spark plug wires also one of mine rubbed against the pcm harness and was arcing to it and caused this same code so I took it to the dealership and they told me I had to put new wires and coil pack before they would put a new pcm on it. My Jeep did the same thing you described in your post almost


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I took mine in for the same thing. After it was determined to be a cylinder head (2weeks of diagnostics) they rolled the diagnostic fees into the extended warranty and all was free. Took forever to get the parts in though.


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Thanks for your comments everyone!

I'll give it a try to the sparkplugs, etc ... and report back as soon as I can do that. My Jeep has 44K miles only. The check engine is gone for the last 2 days, but I know it'll come back.

Cheers!
 
Mando said:
Thanks for your comments everyone!

I'll give it a try to the sparkplugs, etc ... and report back as soon as I can do that. My Jeep has 44K miles only. The check engine is gone for the last 2 days, but I know it'll come back.

Cheers!
Click to expand...

Just in case, the second time I had misfires, I had bad O2 sensors on that side of the engine.


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Update: Replaced coil (#2) and sparkplugs. Check Engine light came back after 50 miles.

Disappointing to say the least ... I guess will bring it back to the garage and see what other options we have or if we have a new code when plugged.
 
*** Update May 2019

So, I found a Jeep garage in town and talked to them about the P0306. They didn't even blink and told me to take it to the dealer, and that I should take it to a dealer they have business with. They assured me that if the code was there, that they would do the cylinder head replacement - no questions asked.

Took it to the dealer, they scanned it, found the code and called me to tell me that the cylinder head will be changed under TSB extended warranty. In the end, Coil #6 was cracked and had to pay for it. Can't complain of the success!

My problem now (after 3 weeks) is that it is finally getting warm in Montreal, and my AC doesn't work. Took it back, and they claim it has nothing to do with the cylinder head (in their experience it is not related).

Questions to forum members:

1) Is the left cylinder head on the driver or passenger side?

2) If on the driver side - don't they have to remove the AC compressor?

3) Coming from a long winter I feel I don't have much leverage with them, but is it likely that they caused any damage in the AC hoses of AC components by doing the cylinder job?

Thanks everyone!
 
Mando said:
So, I found a Jeep garage in town and talked to them about the P0306. They didn't even blink and told me to take it to the dealer, and that I should take it to a dealer they have business with. They assured me that if the code was there, that they would do the cylinder head replacement - no questions asked.

Took it to the dealer, they scanned it, found the code and called me to tell me that the cylinder head will be changed under TSB extended warranty. In the end, Coil #6 was cracked and had to pay for it. Can't complain of the success!

My problem now (after 3 weeks) is that it is finally getting warm in Montreal, and my AC doesn't work. Took it back, and they claim it has nothing to do with the cylinder head (in their experience it is not related).

Questions to forum members:

1) Is the left cylinder head on the driver or passenger side?

2) If on the driver side - don't they have to remove the AC compressor?

3) Coming from a long winter I feel I don't have much leverage with them, but is it likely that they caused any damage in the AC hoses of AC components by doing the cylinder job?

Thanks everyone!
Click to expand...

You can remove the ac compressor from the engine block without having to disconnect the ac lines and move it out of the way to remove the head. No need to suck out the refrigerant.

Ac wise, There could be a leak in the system and if you have never had ac work done before then there will be dye from the factory already in the lines. You can take a black light to the condenser and all the ac lines to see if you can see it leaking anywhere.
 
Thanks Cozdude .. you're right .. my friends at the 4x4 garage put the lamp on and the leak is at the firewall.

Now the question, could the dealer have caused this by not being careful while doing the cylinder head work? Jeep is 2012, but only 54K miles.

I need to know how much leverage I have ... probably very little.
 
Mando said:
Thanks Cozdude .. you're right .. my friends at the 4x4 garage put the lamp on and the leak is at the firewall.

Now the question, could the dealer have caused this by not being careful while doing the cylinder head work? Jeep is 2012, but only 54K miles.

I need to know how much leverage I have ... probably very little.
Click to expand...

We’ll cylinder 6 is on the driver side rear and if it’s leaking at the firewall those lines should be on the passenger side. If so then no you will not have any leverage. To be honest tho I’m not sure how the ac lines are routed on the 3.6
 
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