I've have a mk4 1.8GTI. The missus was using the car today and said the steering wheel went very stiff whilst driving. I've lifted the bonnet & started it up and it sounded rough. I checked the PS fluid level & it was empty, plus I could see in the engine compartment when it looks like its splattered around.

I put some more fluid in, and looked in again & i have a leak !!!!

Standing in front of the car, bonnet raised, down in the left void there is what seems a sensor connected to the PS piping? It looks as if it has approx 25mm nut on it and the electrical connection coming out of the top. The nut is tight, but I can see a small seal at the top of the nut in which looks like the body of the sensor goes into. The seal if hanging out and fluid is coming out at a fair rate of knots when ticking over.
Anyone know what this sensor is? type / part number ??
regards
Steve