Mal wieder ein V6 TDI mit Problemen | Posts 32+

First of all, it's good that the engine is running again.
Your conclusion regarding the repair of the control unit is illogical.

Quote:

...when the transistor fails, it usually has mechanical causes. Also, professionally repairing the control unit is unlikely to be helpful in that case...

You then identify the cause as a mechanically difficult-to-operate pump. The pump is driven by the engine, right? Furthermore, you yourself mentioned earlier that the transistor controls a solenoid valve.
If a semiconductor component fails, it is either due to the component itself (aging), unsuitable environmental conditions, assembly errors, or faults in the circuit.
hg
Herbert.