cooling fan 2 fault please help

[L30N]

Please can you help,

I have a 2003/4 porsche cayenne S

i have read lots of other threads where this fault has been solved by a new fan. this isnt the case with my fault -

A few months back my cooling fan 2 failed (always on, even if I pulled fuse 2 at night and replaced in the morning the fan would ramp up again) and brought up fault P0481 fan 2 control circuit.

Porsche replaced my fan and all was well for a few months. Then whenever my engine was turned off the fan would ramp up for 30-40 minutes non stop.

I returned to Porsche and they replaced the fan again this time under warranty.

This time it only lasted a few hours before it again stays on for 30-40 minutes when the engine is turned off.

A bit of background info – the outside temp here in the uk is 0-10 degrees so very cold and even if the engine is started quickly after not running for a day then turned off the fan starts ramping up as soon as the engine is switched off.

So the engine is stone cold!

The fan does not run while the engine is running. And it runs constantly for 30-40 mins no matter what the engine temp or outside temp is.

fault displayed has always been p0481 and is still the same now.

porsche say the fan is now definately ruled out they will have to investigate further but charge £144 an hour and have no idea how long it will take.

Anybody have any ideas?

thanks in advance

Leon

[bigbuzuki]

Fault P0481

Fan control output stage 2 - open circuit/below limit value/above limit value

Diagnostic conditions

• Time after the engine is started longer than 10 seconds

Possible cause of fault

♦ Break in wiring in power supply to fan module 2 (small/to the left)

♦ Short circuit to ground in control line to fan module 2

♦ Short circuit to B+ in control line to fan module 2

♦ Fan module control module 2 faulty

♦ DME control module faulty

[L30N]

Thanks bigbuzuki thats a great description. i will look into the possible causes you have mentioned