Hi everyone, I am a long time audi owner, first time forum user. Happy to finally find a place that has some answers for these wonderful cars I love to hate. I have a 2000 a4 quatro 1.8t. 6 months ago the check engine light was on, rough idle and poor gas mileage. Took it to the local garage, they diagnosed the problem as misfire in 3 and 4 cylinders. Replaced both O2 sensors, all the spark plugs, and coil packs on 3 and 4. Over a few weeks, all of this was done to the car, each time check engine light came on after 20 minutes of running. Took the car to the VW/Audi shop and they diagnosed the problem as a bad throttle body controller, replaced under warranty for FREE and some broken vacuum lines. Car ran great, until a couple weeks ago, check engine light came on after a very hard start and idle. So bad I turned the car off to avoid potential damage. Tried it again 5 minutes later and no problem but check engine light never went off. Took it to the dealership, Audi and they ran the diagnostic test and determined that the secondary air filter got water in it, froze and cracked. To replace is $500.00 and they said it won't do anything to change performance. Just wondering if anyone else concurs with their verdict and how difficult would it be to do it myself?

 

where is this secondary air filter? never even heard of a secondary air filter....

 

I'm sorry, my wife relayed the info to me. I am looking at the bill right now and I will tell you what they wrote. "Found Fault for Secondary Air System. Found fuse for pump blown. Replaced Fuse, Diagnosed Secondary Air Pump Failure. New Pump installed $550.00" Then they list labor as 2 hours, $10 Fuse, $238 for the pump, $127 for a valve, and $10 for a gasket. Not to distrust them but, ebay has a secondary air pump for $35.00. Would this fix the problem? Thanks for the reply.

 

From what I have read this is a common fault code...I would find an independent mechanic to do the work they might save you a few dollars...if you had the code from the diagnostic tool I am sure someone on here could let you know what the Bentley manual says...

The rough start I am assuming came in pretty cold weather...I have had the same problem and my VAG lists a problem with the secondary air flow as well...I am taking mine in on Tuesday as the CEL comes back on after about 200 miles or so of driving...it usually is a leak in a hose or from what I was told by the dealer the combination valve could also be bad...but I doubt it should be more than 300-350 (what they quoted me based on past repairs) to fix...my car is a 2002 though but I can't see how that would make that big a difference in the price....some cars however have this CEL come on and if cleared probably won't come back....just what I found out while I was researching this about a week ago...seems to be more common with VW than Audi...

 

Thanks for the info. I probably will take it to a very good independant mechanic in town, he actually does a lot of work for a used car dealership that specializes in Audi, BMW, and Merc. I just wondered if it was a repair that could be undertaken by someone with a spare Saturday.

 

The best way to find out if you could do it would be to find the code that CEL is being triggered by, post it, and then let someone tell you what is recommended...at minimum you would need something that could test for leaks in the system...and then be able to test any valves that could be related...