mfts symptoms?

[UrS4boy]

This link says nothing about the ABY just about the AAN ! As it happens this is one of the only things the the ABY/AAN differs on on ecu pinout.
The aby ECU is connected to the MFTS so it is possable that it could affect boost.

ref. http://s2central.net/motronic_pinout_ABY.html

My bad. I had forgotten that the ABY ECU does use a MFTS output whereas the AAN does not. (We had that debate here some time ago but I forgot about it until you posted. Sorry).

Most of my info is AAN-related (because I have an UrS4). A lot of it translates to the ABY but, as you point out, not all.

One link that you *might* find useful is this AAN engine bay device map. YMMV.:

http://forums.audiworld.com/s4s6/msgs/222453.phtml

I could do one for the 3B if somebody had a jpg image of a 3B engine bay.

[ifa]

If you have the automatic climate control, it is possible to check the MFTS output to the coolant temp gauge against the coolant temp going to the heater by using Channel 51 of the climate control as described here:

Clima reading comes from sender in the heaters hose not mfts.

[UrS4boy]

Clima reading comes sender in the heaters hose not mfts.

I know but you can still use the climate control temp reading to compare to the water temperature gauge (clock) that DOES get its signal from the MFTS. You can also use the Ch. 51 reading to confirm that the thermostat in the block has failed open and it's just not the MFTS temp sender that has failed.

[ifa]

Learning to read. My bad.