Well I have had the Audi for about a week now. I am pretty knowledgeable with the M3 so I hope to learn more about the A4. I took a trip to the beach this weekend and everything went well. The car drive straight, comfortably, and no noticeable issues until on the way back when the check engine light came on. I stopped and nothing looked out of sorts and didn’t smell anything, so I cautiously continued on the way home watching the gauges hoping to not overheat. I was about to read the code with my friends generic code reader and it gave me code P0411 which is "Secondary Air Injection System Flow Incorrect.". I thought maybe it could be a vacuum line or what not, but don’t even know where to look at. Anything else I should be looking at?

I might just take it to the shop my father goes to and let them fix that and have a once over on the car. It is a 2001 A4 1.t with 73,000 miles. Previous owner has the engine de-sludged and timing belt/water pump replaced.

This is going to be my daily driver and want to keep her in working condition. The M3 will be retried to show/weekend car status.

 

The CEL is rarely if ever related to anything that serious, other warnings will pop up if there is a more serious issue. Of course you want to scan the codes as soon as possible, but you could easily have the light on for months at a time depending on the problem and how quickly you're willing to act on it. That light has more to do with "out of spec" emissions than anything else. (And you can't pass a smog test until it's cleared.)

Don't bother with a generic reader. Do you have a Windows-capable laptop? A Mac works too if you can install Windows via Bootcamp/Parallels/vmware. Buy a cheap cable such as this one:

USB VW Audi Interface Scan Tool Code Reader Cable VCDS 409 1 FT232BL OBD2 OBDII | eBay

Then go to ross-tech.com and download the free version of "VCDS-Lite". (Formerly "VAG-COM".) You will scarcely find a person in this forum not using VCDS to scan codes. It scans the full Audi/VW codes which are much more expressive than the generic ones. Then you can decode them and look at suggestions from this page:

Category:Fault Codes - Ross-Tech Wiki

Good luck!

 

Common code with these. I would check vacuum lines in the back of the engine, check if anything got disconnected around the secondary air pump. Also check the combi valve ( It in the back of the engine, on top, round part about baseball in diameter). From previous experience with older Audis combi valve is the issue. I hope this helps. Good luck

 

What the dealer does is disconnect the battery and the light goes away for a few days. So shitty. Exact same thing happened to me. I don't have to pass emissions where I'm at so I haven't focused on it to much. The SAIP sucks clean air from your intake box. On my 99 there is a small (as big around as a quarter) hose coming off my air filter housing. When u first start the car you should feel suction from this hose. If you do your pump is fine. Anybody know an easy way to check the combi valve?

 

Thanks! I am sure over time I will more comfortable with the car, just freaked out a little since i just got it. I will def look in ross-tech site. Thanks for the heads up and helping me out.



I will have a look at the vaccumm lines this weekend and see if I see lines that are not connected or torn. Thanks for the help!

Ill check all the hoses this weekend and see what I find. If you find out how to check the combi valve, please let me know. Thanks again for the help.