Where the heck is my AUC sensor?
 

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Hi, I have an 08 535xi wagon N54 engine, I have a 9c54 fault telling me the AUC sensor is bad, Is it supposed to be on the cooling fan shroud? All i can see there from front looking back on the LH side
is a large connector that has heavy duty cables attached like it's the fan motor plug? Looking at AUC sensors online they look a fair bit smaller, any help with this would be much appreciated before i purchase the part.
Thanks

I think I know where this is located. I changed the cabin air filters yesterday and noticed this strange little sensor that I had no idea what it was. I looked up the AUC sensor and that appears to be it. It is located on the front edge of the passenger side cabin air filter lid if I was looking at the right thing. Check it out. Take off the lid and it should be attached.

Yes, you were right, thank you :-)
Seems strange to me that according to some sources, this little thing can make your engine cooling fan run?
A few weeks back my fan started to run on high (never heard it before in 4 years of ownership) and then cut off just as quickly as it came on
and in all my research (many were saying new coolant pump) and testing of the cooling pump i came across a few threads that siad it might be this
and also i have a fault code related to it so.............here's hoping :-)

Hopefully that will fix your issue, and glad it is where I thought it was, I didn't want to sound like a shidiot.

Well done folks. I also have an error for mine but no issues with the radiator fan. I wonder if I can temporarily put in the one from my E46. But I think that one is in a large larger piece.