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FIXITMAN, Master Technician
Category: Audi
Satisfied Customers: 17368
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Audi A4 Quattro: 2009 A4 Quattro 2.0 with 90,00 miles. Dealer

Customer Question

2009 A4 Quattro 2.0 with 90,00 miles. Dealer serviced at all recommended intervals. Persistent MIL since 12/2015. Took it in for service in May and at time the MIL was diagnosed as intake manifold issue. Replaced manifold, cleaned valves, drove it 4 days and MIL returned. This time diagnosed as low boost issue with turbo...P0299...replace turbo, which I have not done. Purchased an OBD II scanner and confirmed code. Reset it and the MIL did not return for ~12 days of normal driving. It did return though and out of disgust I did not check it right away. Finally did this week and the only code present was the 301 for the misfire in cylinder 1. Have replaced all coils and plugs. Threw the scanner in it and 301 code is pending. Not sure where to go from here. There's nothing noticeably wrong with the performance. Just trying to get the vehicle ready to trade (with a clean conscience) before additionl maintenance cost arise...brakes, battery, etc. Thanks
Submitted: 2 years ago.
Category: Audi
Expert:  FIXITMAN replied 2 years ago.
Hello, my name is Bobby. Thanks for the question. From what you are explaining it sounds like you may have had a catalytic converter issue. This will cause boost issues as you had. I would not go in that direction yet. Since you have a misfire I would do a compression test on the engine. I have had a lot of these engines have slightly burnt valves which will cause this to occur. Was this ever done?
Customer: replied 2 years ago.
Thanks Bobby. No, I don't believe the compression has been tested. If I had any faith that the next repair would take care of it, I'd do it or have it done. From my perspective, they may as well replace the MIL with a strobe light. As I said, I'm going to trade the vehicle, but wanted to get it right before doing so. Unfortunately, this thing seems to be a giant rabbit hole sucking good money after bad. I guess a follow-up question to the question I should have asked in the first place is whether whether the 301 misfire could be related to the 299 turbo issue and what would cause the turbo code to resolve itself. It was explained to me that the 299 code was thrown because of slop in the connectivity mechanism between the turbo waste gate rod and diverter. Can't figure out how that goes away on its own and get replaced by the 301 misfire. I haven't altered my driving habits or style and P299 is no longer being detected. Thanks.
Expert:  FIXITMAN replied 2 years ago.
The turbo issue may haven one up due to some build up on the mechanism and that has since freed up. The turbo issue will not cause a misfire on only one cylinder this is why I am recommending a compression test.