A few issues with my 2007 A6 4.2l
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Joined: Jul 2014
Posts: 502
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From: Chicago Suburbs
A few issues with my 2007 A6 4.2l
Fuel Pressure Regulator Valve; Bank 2 (N276):
The P129B - 004 - Open Circuit code appeared.
This problem has been interrmittent for some time but the car ran fine. The other week my wife came home and said that the EPC light came on and the car was shaking at idle.
Instead of throwing parts at my 2007 Audi A6, 4.2l I measured the resistance of the HPFP coil on both banks, bank 1 read 1.5 ohms and bank 2 was open. I then checked the voltage on the connector going to the HPFP coil and read 10.5V. (The low voltage may be due to the Battery Regulator issue).
Comfortable that the problem was with the bank 2 HPFP, I ordered one from ebay (the local parts stores wanted 2X the price. Installed it today and the EPC light was gone and the car ran like new again.
Expansion Tank:
I also replaced my expansion tank since it developed a small leak, second time for this replacments the last one was 100K miles ago.
Battery Regulator:
I also been getting random error codes related to electronics and battery regulator. When I was letting the car sit for a week I noticed that the battery was low. The alternator seems fine as the voltage went up with the engine running.
The battery is only 4 years old (purchased from Audi dealer) and coded the new battery. The previous battery lasted 7 years.
Any suggestions on what parameters I should look at regarding the health of my battery?
The P129B - 004 - Open Circuit code appeared.
This problem has been interrmittent for some time but the car ran fine. The other week my wife came home and said that the EPC light came on and the car was shaking at idle.
Instead of throwing parts at my 2007 Audi A6, 4.2l I measured the resistance of the HPFP coil on both banks, bank 1 read 1.5 ohms and bank 2 was open. I then checked the voltage on the connector going to the HPFP coil and read 10.5V. (The low voltage may be due to the Battery Regulator issue).
Comfortable that the problem was with the bank 2 HPFP, I ordered one from ebay (the local parts stores wanted 2X the price. Installed it today and the EPC light was gone and the car ran like new again.
Expansion Tank:
I also replaced my expansion tank since it developed a small leak, second time for this replacments the last one was 100K miles ago.
Battery Regulator:
I also been getting random error codes related to electronics and battery regulator. When I was letting the car sit for a week I noticed that the battery was low. The alternator seems fine as the voltage went up with the engine running.
The battery is only 4 years old (purchased from Audi dealer) and coded the new battery. The previous battery lasted 7 years.
Any suggestions on what parameters I should look at regarding the health of my battery?
Last edited by A6 4.2 Vier; Nov 23, 2023 at 04:49 PM.
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