I'm one of the unlucky not managing to solve this (even with the help of local garage, probably need to ask local Audi to change the whole engine next as the last resort...).
So far done:
- Removed and cleaned intake manifold (wasn't that carbonized actually).
- Changed "all relevant parts" (G336 potentiometer, solenoid).
- Checked correct movement of the flaps before re-installing the manifold
So what happens now:
- Idle: No error code. Channel 142 (VCDS) shows value of 100% (both for target and actual value).
- High RPM: Error code 17439. Channel 142 target value 0%, actual ca. 40%. However, the actuator works perfectly and in my opinion the flaps reach the target position. If I gently push the rod with a screwdriver, there's no visible movement but the value may drop slightly as the flaps and rods may bend slightly (say 5%).
Tried basic setting of channel 142, but it says "ERROR" instead of "ADP OK" - probably because 0% value hasn't been achieved.
The fun thing is I've found a couple of forum posts here and there with exactly the same problem (including the post above), some even with the same VCDS channel 142 outputs - however in none of the cases have I found if (and how) the problem was cured in the end.
So, finally, my question is: Has anyone got any idea what to do next? Is there some secret "basic setting" that needs to be performed with a new potentiometer? Could it be a problem with the wiring, ECU, or something else? Does anyone know what should be the resistance (in ohms) for the potentiometer in max and min positions?
Any help would be very much appreciated!