Laubergiste

After leaving the window open on front passenger side, and 2 hours of pouring rain, a lot of water was inside the car. That day the car functioned properly. The next day, the car lost the P R N D S display in the dash, the tachometer was only sporadically working, and the Oil warning light and check engine light came on, and the car would shut the engine after 5 seconds. I looked online, found out that the computer under the passenger seat was under water, lifted carpet, took it out, dried it, put it back in. All lights in the dash are back to normal, no warning on. BUT: the car only runs in 4th gear (I can see number 4 displayed when I switch to tiptronic and it wouldn't change gears in tiptronic either. To make things more complicated, after 20 or so minutes of driving, it starts shifting gears automatically and in tiptronic mode too. The next day, it starts again in 4th gear, and the story is the same, after 20 or so minutes of driving, it gets normal. I ordered today a VAG U600 scan tool, I hope to use it to clear all error codes. How can I get rid of the limp mode?

Kneale Brownson

There is a separate transmission control unit (TCU) for the tip. That probably got wet too and now has corrosion. I don't know the location of the TCU in your car, but someone else probably will.

Peter Badore

I have never seen any kind of separate control unit for the tiptronic function? It is always part of the now wet control module under the passenger seat. Could the 3.0l V6 be different from all the 2.8l V6 engine A6s and A4s that I have worked on? Probably to fix the limp mode problem a new TCU will be needed or take the wet module apart for corrosion inspection as well as the connector to the main wiring harness.

Kris Hansen

Me either, but one never knows. I suspect that something is still wet, and given enough heat and drying time, it may revert back to normal.

Laubergiste

The wet device stayed 2 hours under a fan. Then I used a compressed air spray to blow any wet spots under the electronic components. Now I have all 4 carpets raised up from all corners so it gets dry. The device under driver's seat was dry inside the plastic box.
What puzzles me is the fact that after a while (~20 mins), the car switches back to running normally. Then when I leave office or next day, again it starts in 4th gear.