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Old 03-15-2014, 07:34 PM
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2011 Jeep Grand Cherokee po304 code

I have 2011 jeep grand Cherokee with the 3.6 engine. I have 40000 miles on it.
On Wednesday my check engine light came on , so I took the negative terminal battery and the code went off. Then I put fuel injection cleaner and threw in super gas in it and 2 days later the light came on. Does any one know what it's could be. The po304 is the code.
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Old 03-15-2014, 11:02 PM
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Re: 2011 Jeep Grand Cherokee po304 code

A code P0304 may mean that one or more of the following has happened: Faulty spark plug or wire Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel Poor compression
Defective computer
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Old 03-15-2014, 11:14 PM
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Re: 2011 Jeep Grand Cherokee po304 code

Thank you. That's what I saw from Google it. Was trying to see if someone had the same problem and what was the problem
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Old 03-16-2014, 03:41 AM
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Re: 2011 Jeep Grand Cherokee po304 code

I would guess it is the O2 sensor, as they can sometimes throw a code when you change from say E10 to V-Power + additive.
I would try another ECU update or get a CANBus scanner and clear the code. is the Check Engine Light (CEL) on ?
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Old 03-16-2014, 08:29 AM
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This is most likely NOT an O2 sensor issue. P0304 is a single-cylinder misfire detection on cylinder 4. Could be plugs, ignition coil, or compression related. Keep in mind that there were a number of 3.6L V6 engines early on (known issue) that developed cracks in the cylinder head which usually showed as a single-cylinder misfire because of the compression loss. You can't rule that out either.
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Old 03-23-2014, 04:24 AM
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Re: 2011 Jeep Grand Cherokee po304 code

Have a look at this tread: Cylinder head Problems
I got a new cylinder head at 44000 km as the engine was running rough and there was a loss of compression in cylinder two (my error code was P0302 but it also happens at other cylinders). It is a manufacturing fault but as usual they won't tell you exactly what it is.
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Old 03-23-2014, 11:07 AM
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Re: 2011 Jeep Grand Cherokee po304 code

Had same code in February on 2011 Grand Cherokee with 36,000 miles. Service dealer replaced cylinder head per diagnosis "for misfires on cylinder four the valve seat on sealing." Under warranty. Service dept says it is fairly frequent problem with 3.6 engine. Told that Chrysler now stocking cylinder heads for regular replacement.
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Old 03-23-2014, 07:10 PM
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Re: 2011 Jeep Grand Cherokee po304 code

MY11 3.6 ~53,000klm

MIL light on ...often. Multiple O2 sensor replacements, heads replaced, cat converter replaced, software upgrades applied.

Towed to the workshop 9 working days ago. Might get it back tomorrow. Rental vehicle provided for the past 9 calendar days.

Nearly 2 years of this problem. "He bought a Jeep..." Big mistake!!

Regards
Bernard
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Old 03-26-2014, 05:32 AM
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Re: 2011 Jeep Grand Cherokee po304 code

Bring in the lemon laws, and enforce them.
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Old 03-30-2014, 08:39 AM
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Re: 2011 Jeep Grand Cherokee po304 code

They have to replaced the head on it.
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Old 04-01-2014, 11:41 PM
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Re: 2011 Jeep Grand Cherokee po304 code

UPDATE:

Picked it up from the dealer today. 3 weeks since it was delivered to them by tow truck. I had a rental vehicle for about 2.5 of those weeks (including 2 extensions of the rental period).

They did not even have the statement of work finished (even though they called me yesterday to say that it was ready) but included replacement of the ignition module and oil pump. (Heads replaced last July.)

I will post the full story when they send me the full set of documents. If they don't Jeep have indicated that they will request them for me. Actually Roadside assistance and Jeep have been quite helpful and I have definitely received more information from them then from the dealer who for the last 2 weeks have only sent me 3 emails telling me that it was not ready yet. This is despite me calling them a number of times over that period asking what was happening.

Apparently the replacement parts have a 12 month 20,000k warranty. The vehicle warranty expires in Dec this year.

I am over it... Time to look for a replacement vehicle that does not have the same logo on the steering wheel.

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Bernard
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Old 04-02-2014, 01:53 AM
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Hmm interesting. What are you going to look at? Im a bit in the same spot but think I'm going to wait and consider the new ford Everest next year.
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