Audiforum first timer post. Need to comment on multi month 2006 A3 2.0T Check Engine light and cylinder #2 and random misfire codes. Car had some cold start shakes and when warm, ran great.

I was getting extremely frustrated with a persistant CEL and ECU misfire code.
Needed to go back and forth between Private mechanic, Audi dealer mechanics and internet posts to come up with a strategy to fix that didn't involve a $1600 "shotgun" approach to get the check Engine light to go away.

First trip to dealer resulted in error code clear and evaporator valve and hose replacement. Dropped close to $400 there. Also received new coil packs for all cylinders under 2006 A3 recall. CEL promptly turned on very next
day. Also Received "free" assessment that my A3 needed approx $2000 in routine maintenance at 75K mileage to boot.

Looked over suggested work, most of it legit, and found private mechanic to do same for 30% of the dealer rate. Also reset CEL for misfires with the hope that it would just go away. It did not. Next day on.

Now inspired to take fate in my own hands, I googled and read every thread I could on Audi 2.0T Check Engine scenarios to come up with a way to make the problem go away permantly. What I learned thru this effort is that all Audi FSI engines are prone to carbon build up. The Intake design essentially guarantees some level of carbon buildup on the air intake. I decided that my first attack on this problem was to have my private mechanic perform a de-carb on the intake manifold. He spent about 5 hours on that job, mainly due to long process of removing and re-installing intake manifold. Actual cleaning requires intake chemical cleaner, elbow grease to scrape off buildup and approx 1 hr of set time for cleaning agent. After done with CEL reset, light came back on very next day after cold startup.

Now even more frustrated, I take car back to dealer, convinced they have better diagnostic tools than anyone. The want to perform cylinder leak down and compression testing upon a cold start environment. I leave car overnight, they run tests next day. Service Manager calls back and says they found an air intake hose broken/disconnected, that they need to replace. They report that leak down tests "passed" and compression was in the 150+ range for all cylinders. The intake hose was replaced CEL reset. Dealer advised that car intake manifold was "scoped" and should be cleaned. Also suggested that cylnder #2 fuel injector likely should be replaced. Fee would be $1600. I'm mentally thinking the dealer should now pound sand and I gracefully tell them no thanks and take my car back. Dealer wants me to compensate them for their "diagnosis" and hours spent on car. I offer $150 to cover that cost as I say some value in the leak down and compression tests. New bill $250 and I take my car back.

Now I go into info overdrive on internet to find out what is going on. I'm thinking that the manifold is clean and i should invest in heavy duty fuel injector cleaner. I decided to go with BG 44K cleaner bought online and to go with "italian tuneup" style of driving with sport mode on Stronic transmission. After two tanks and CEL still on, I call up private mechanic to set time for fuel injector replacement on cylinder #2. While I'm drving my son to a far away weekend soccer game, incredibly the CEL turns off. And it is staying off.

I'm giving the credit to the private mechanic and the de-carb cleaning + the BG 44K gas additive. Also thinking the dealers are good for warranty work and struggle to suggest sub $1,000 fixes to out of warranty problems.

 

Similar story with mine. The dealer can never find the problem. Did their fuel system cleaning. Helped for a few weeks. Our CEL comes on and off with no type of pattern. I have ignored it now for a year. Only trouble is when inspection time comes. Have to be tricky then.

 

shooting in the dark, but what octane gas do you use? I know premium is expensive, but I had a friend that used 89 and had similar issues that you are referring to. I throw in a bottle of STP about every 6 fill ups-- never had any problems with that and using 91 octane.

 

i've been having same problem...going in circles with Audi of America and dealer, with each claiming "no issue to resolve". Here's my full story: https://www.audiforums.com/forum/aud...verter-202754/