# Help with trouble codes: p0300, p0301, p0304



## Eurorescue (Nov 7, 2010)

About 2 weeks ago, I got a flashing check engine light on startup and a bumpy idle. I turned off the car and back on, and both issues were gone. I subsequently took the car to the dealership hoping it was the intake flapper motor to be covered under extended warranty. NOPE, got these three codes pulled. TECH showed me the airbox had a crack in it PRE MAF and cited this as the problem for the misfires. He said it would cause the car to run lean. How on earth would a vacumn leak PRE MAF cause a lean condition, and only on two cylinders? 

In addition, the tech noticed oil in the coolant overflow bottle. While the tech was in there, he replaced all four coilpacks under recall, buttoned up the motor and gave it back to me. 

So today, I start the car cold for the first time in a while and I get the same flashing CEL and bumpy idle. Turned it off, and back on again for it to be just fine. Drove to Autozone to have the codes pulled and I get: p0300, p0301, p0304.

Autozone printout says most likely cause is lean A/F due to vacumn leak. Also adds 3 other possible causes: Ignition system fault, fuel injector fault, and engine mechanical condition.

SO... Anyone have any ideas as to what could be wrong with my motor? I only have 82K on it, and its acting up a lot lately. BTW, i have an 06 A3 2.0T with 6MT. 

EDIT: I replaced the spark plugs at 55K miles with NGK's one heat range colder. The only mod on this car is an EIP CAI.


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## x9t (Sep 19, 2005)

.. carbon build up can cause missfires or maybe injectors.. I guess you would have to run some logs.

JT


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## vdubaz (Jul 12, 2011)

Euro,
Any word on what was the cause for the misfires?

I have 138k on my '07 GTI and i've had this issue for over 4 months now and i'm hoping to find the cure.
My independent vw shop is looking at the car next week and i'd like to see if I can throw them some possible causes.
So far PCV, Plugs, Coils, and Purge Valve have been replaced on my ride.


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## xtravbx (May 21, 2005)

w/ 138k i'd be worry about carbon build up.

obviously fueling too - cam follower, hpfp, etc.


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## fantonio (Feb 12, 2012)

*Same here*

I have the same 3 codes and high mileage....hopefully someone will have an update


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