Tiptronic and the brake light switch! A saga...

[Greenpigeon]

What initially appeared to be a major tiptronic gearbox fault on my B6 S4 Avant turned out to be a result of a sticky brake light switch, sending a faulty signal to the torque converter and preventing auto up-shifts. Replacement switch fixed it.

Problem is, it took the replacement of the gearbox valve chest/wiring loom and the mass airflow meter before the light switch was diagnosed. Beware!

May be worth replacing the switch as a precuation, because I gather from Audi that the effect on the torque converter can be serious.