Audi Repair: 2004 A4 1.8T CVT showing fault 18201-P1793, ribbon cable, faulty sensor


Question
It comes on and sometimes resets itself. From researching on the net I find that Audi has issued TSB #370710 which suggests replacing the TCM. My car, bought used, already has 65K miles on it. Besides the CEL, it seems to be driving fine. It doesn't have any of the drive gear light flashing (or any of those symptoms). I've reset the DTC faults a few times with a VAG-COM, it keeps coming back. I haven't noticed a discernable pattern as to what triggers it. Logging some runtime data with the VAG-COM with a drive around the block shows identical readings from sensors G195 and G196.

1. Since the vehicle is out of warranty and they didn't figure it out until almost the end of the warranty period, is Audi America likely to cover the problem since they shipped a faulty module?
2. Is this problem benign or should I have the TCM replaced right away?
3. Is this repair a DIY and/or can it be done by a shop other than the dealer?

Let me know if any additional information is required.

Answer
Hi,  You have already got into a good deal of detail.  In my experience, the ribbon cable in the transmission often oxidizes and starts giving bad connections, whcih can lead to strange problems.  If the driving is not affected, the problem can still be real.  CHances of getting Audi to cover a 2004 vehicle transmission are pretty slim I'd say.  If you want to do the checks yourself, this is beyond the normal DIY level repairs I think.  I would contact a good local import specialist and have te problem diagnosed; a TCM replacement sounds too drastic to me.  More likely a faulty sensor or input.  Good luck,  Jan