2000 A6 4.2L TCU problem
 

So the TCU in my 2000 A6 4.2 (4b0 927 156 BS) has gone bad (causes the transmission to stay in limp mode). Before I bought the car, it had been chipped. I realized that putting enough pressure in the right spot on the TCU would cause it to start functioning again. However, over time, this method has proven less and less effective.

Last week I found a TCU for a 2001 A6 4.2 (4b0 927 156 CT). I was not able to find any documentation either way as to whether or not it would work. I bought it anyway. It does not appear to work at the moment, transmission still goes into limp mode. What I did notice, however, is that for the first 15 seconds or so, it is working properly, and does shift as it used to.

I used my vag-com, and found that it was pulling a 18156 error which reports a programming error. Is this something I can overcome and reprogram with the vag-com, or do I need to just re-list it on ebay? I have looked all over for the right TCU, but I can't find it anywhere. Any help would be appreciated!

My other question is can I pull the chip out of my old TCU (it sits on a riser board) and put it on the new one? Without opening the new tcu, I don't know if it sits on a riser as well, or if its soldered directly to the motherboard. If anyone new the answer to that question, I can try that option.

2000 A6 4.2L TCU problem
 

do you still happen to have "4b0 927 156 CT" and are you interested in selling it?

Went thru this on mine
 

Also a 2000 4.2 with a "BS" TCU. Had a tranny chip that likewise came unsoldered over time. Finally just replaced it w/ another "BS" suffix box I found on ebay or via car-part.com (don't recall which any more).

I have 2 of the 4b0 927 156 BS units for sale if anyone needs one. $500 ea. Call/Text 618-558-5539.

Welcome! Opportunists are always a great addition to a tight-knit community. I sold my identical TCM a year ago for $150, which was a fair price. Doesn't this belong in the classifieds section?

Is it possible that the programming problem is not what's causing the limp mode?

If you sold your tcm for $150 you gave it away. I looked for a month to find the one I have and it was the CHEAPEST one I could find at $550. I will be losing $50 on it actually. I'm here to get help with my car just like everyone else. Not trying to make any money. I know how rare these tcm's are and I thought I was helping out by posting it.

Disagree. That's pretty much the going rate.

BTW, you guys do know that this post is several months old, right?

Ouch
 

I did a 6sp swap, and had the identical TCU left over. Sold it a month ago to a guy on AUDIZINE for $200. Guess I should have advertised it first. Oh well.