I have a 2005 A6 3.2 which about a month ago developed an erratic idle when cold, then when driving for the first mile or so it surges ever second or so. After the first mile the problem goes away.

When it first started happening about a month ago, the check engine light came on. I scheduled a visit to the dealer, but the light turned off the next day and the surging did not. Light has not come on since. I am hestitant to bring it to the dealer for the $125 computer diag read (appliable to the repair) when most likely with the light off the code is gone as well.

Any thoughts? My first thought is there is a sensor somewhere that is a miss.

I really appreciate your feedback!
Thanks,
Greg

 

I am guessing carbon build up. It is a known problem with the FSI engines.

 

Carbon build-up started in 06 w/ Direct Injection