I am writing in this forum to hopefully get some answers..I broke down a couple days ago in my audi a4. I have only had this car for a couple weeks now, I bought it new/used and it seemed to be in pretty great shape. No problems in the two weeks I was driving it before I broke down.

I drove into work like I usually do (about a 20 minute drive) and I noticed it was driving a little rough. I felt that it was having a little trouble accelerating especially over 40 mph. I stayed below 40 mph and it was still a smooth ride. I parked it at work and plugged in my code reader because the engine light was on. I got two codes, P0171 and P0491. Both codes having to do with the air system going into my engine. After work, I began to drive home and the car was running fine, I got to the first top sign after driving for only about 30 seconds, and the car would no longer move. Everything was still on, the lights and the engine but when I pushed the gas it would not move forward or in reverse. I tried turning the car on and off, but still nothing. I had to put it in neutral and roll to a safer place to have it towed.

Once I got it towed back home, I looked up common problems with the same symptoms. I reached the conclusion that it was my TCM (transmission control module), and after erasing all the codes for my engine it would drive normal for a couple seconds and then die again like it did when I broke down. The only thing is, I did not get ANY warning lights besides the engine codes I already stated, and when the TCM goes bad, most people say that their gear shiftier flashes. Mine did not.

I went throw my car trying to find the TCM, ended up unplugging/re plugging my ECM and all these other computer parts all over my car because I was looking for the TCM specifically. I reset my battery, changed my oil, did all my spark plugs, and found that the vacuum leading to my engine was basically unscrewed so that fixed all the air system codes I had before. I also replaced a very warn fuse connecting the ECM. After calling an Audi dealership I learned that the TCM is under my car, above the transmission. I brought my audi to my local shop to hopefully save some money and asked them to remove it for me. But heres the thing, after basically resetting everything in my car besides my TCM, it runs fine. I can drive around the block, to a different town, without it dying on my like it did before. I drove it to my local mechanic anyways.

HOWEVER, the mechanic at the shop told me he located my TCM and it did not look worn or bad. He did hook up his code reader specifically for the transmission codes, and he pulled one code: audi code 18161/ F189. This has to do with my tiptronic switch which is located in my gear shifter. I read that a magnet could be off or worn, and so on. But I haven't had any problems gear shifting and when I took the shifter apart to look at the tiptronic switch, it looked clean and perfect.

I do not know what to do, I am afraid I will get stuck again but I still want to drive my car around because it seems like it is fine. Has anyone had this happen to them before? Any suggestions? The mechanic seemed to think it was a one time malfunction and maybe it was the fuse I replaced, but I am not convinced. Any suggestions would help! Thanks

 

I am with you in that I have trouble believing just resetting something will fix the problem. In the end though you could be throwing money at a problem that isn't there. I would drive it and see if it reappears.