# A6 4.2 Transmission Limp mode P1748 Programming Error



## Drewhastheinternet (Feb 12, 2014)

Hello 
I am working on a 2000 Audi A6 4.2 and the trans is stuck in limp mode causing it to bang into reverse and start in 4th gear. 
Just wondering if anyone else has seen the P1748 "Programming Error" code when scanning the TCM?
Also I don't understand why in the measuring blocks the terminal 15 voltage drops to 0 when the engine is running 
Watch the video for a full explanation of the problem and what I have done so far


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## Drewhastheinternet (Feb 12, 2014)

I have come to the conclusion that the TCM is bad in this car. I will try a new one as soon as I can find a replacement


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## Drewhastheinternet (Feb 12, 2014)

It was the control module! put a new one in there and bam! first gear is back 
Not sure why I am seeing so many A6 cars with bad TCMs ?? just a couple weeks ago I worked on a 3.0 A6 that had problems with it's shift interlock circuits and after testing every part of that system I concluded that the TCM was at fault. Ordered a replacement and sure enough that was the issue. The car would not shift out of park :banghead: cant imagine that was a fun day for the owner lol


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