Boost Pressure Problems: N75 & Manifold Pressure Sensor

Question for the experts:
Can a faulty wastegate control valve (N75) affect the intake manifold pressure sensor (G71 - is this actually located in the engine control unit for the 1Z engine?) to the extent that an error code 00519 (short circuit to positive - intermittent) occurs?

Basically:
Why do N75 valves fail? I've noticed on my Passat (which has been modified with silicone hoses for the small pressure lines) that small amounts of oil are leaking from the crankcase ventilation system to the N75 valve and the EDC. This can only be harmful, especially if there are rubber seals inside. Has anyone found a workaround for this problem?

Best regards, Steffen.