I have a 2008 A4 Quattro. The car has over 80,000 miles and has had no maintenence other than oil changes. I was planning on changing the plugs and air filter this week.

This weekend I was on a long road trip and my check engine light came on immediately after I checked my oil at a rest stop. Assuming it was just a loose fuel cap, I got back on the road. When I exited the highway I noticed that the car would rev up to 2000 RPM when idling and then drop down to normal. The car was fine at highway speeds.

My mechanic took a look at the car today and siad that several codes came up on the computer and that the car was running lean. He's not sure yet what the problem is.

Any ideas or comments would be appreciated.

 

Its definitely time for new plugs, air filter, fuel filter, and a maf cleaning (if the b7s have those). I would also run some fuel injector cleaner next fill up.

As far as running lean and idling like that, check for vacuum leaks. Probably just a hose needing replacement.

 

Thanks for the info. I was very surprised that Audi does not recommend replacing the fuel filter as part of their maintenance schedule on this car. Regarding the leak, that sounds right but my mechanic can't seem to find it....

 

Ask him to perform a leak down test with indicator gas. If that doesn't show any leaks, it could be an issue with a sensor.