Scott Bell

Was working in the garage and the engine exhaust fan turned on out of the blue. Didn't touch or have key in it. 30+ hours cold. Continued to run for over an hour before unplugging it. Later in the day I plugged the fan back in and all OK. Then I opened the door and it came back on and ran until unplugged. Began trouble shooting, relay tests good. The fan plug was still getting voltage with the relay removed. To the harness...........Checked connections and wire continuity, still voltage. Unplugged harness main connector, retested, then reconnected. Suddenly, issue is no longer there. WTF?

wyovino

Engine bay temp sensor?

shft22

Based on my limited experience, having 12v with the relay removed is OK. Don't know the logic for it, but apparently Porsche switches ground, so 12v is alway present.

DBJoe996

Porsche, along with most other car manufacturers use the ground, or negative lead, for switching stuff on and off. Having a constant 12V at a particular plug such as the harness for the fan is not the problem, it is the ground or negative lead that determines whether it is on or off.

808Bill

Maybe mice? They love wires!

Mike Murphy

I would start there. If cheap, just replace it.