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Discussion Starter · #1 ·

I went away for four days, come back, and now when opening the doors or driving the Cayenne, the fans stay on constant, they turn off after locking the car.

Checking the code looks like needs a new fan unit but it has to be the whole unit from what I can see and have read the control unit is on the whole fan unit and so need to spend a chunk of money.

Two questions - Is any easy fix I'm missing (error code P0480 - circuit control unit 1) // Is there an OEM part for this rather than full-blown Porsche costs? (I have read about Volkswagen parts but am uncertain if this is correct)

Sorry if stupid questions dug around a bit, but literally only bought a month ago and was driving fine, then parked up for four days come back and it just started randomly.

I have put the battery on CTEK and charges to full and holds charge ok.

Thanks for the pointers, help, and advice.


3 Posts
Sometimes the fan comes on because the car and it's predetermined objectives have sensed an issue where the car would feel better if the fans were on. If you have the ac turned on max you will sense the compromise the engineers made to provide adequate cooling. The car is very intelligent most of the time, and will demand of you oil and bludef (my cayenne is '13 diesel so it needs that) and occasionally other things, such as a broken tail light lens or coolant for the radiator. The fans level of notches will activate the ac second tier of blowers which are loud and unpleasant and if you left them engaged when you stepped out of your car, they will remember to howl for you on your return. rb

110 Posts
Hi Stewart, welcome to Cayenne Forums.

You've read a code indicating "circuit control unit" P0480?

Here is the official explanation of that code from Porsche:
Porsche said:

Diagnosis information - Control unit DME (DFI)

Final stage Radiator fan control module

Open-running fan blades.
Danger of limbs being cut off.
Risk of serious injuries due to foreign bodies being thrown out.

  • DO NOT allow hair or clothing close to the rotating range of the fan.
  • DO NOT reach into the rotating fan.
  • DO NOT place tools or other items in the rotating range of the fan.
  • Perform work on the fan only with the ignition switched off.
  • Secure the ignition to prevent accidental switching on by other persons.
Sensitive electronics.
Risk of irreparable damage to electronic components.

  • DO NOT perform electrical tests.
  • DO NOT connect external power sources.
Diagnostic conditions

  • Ignition on
Possible fault causes

  • Short circuit to ground or open circuit in lines (Power supply Radiator fan control module Terminal 30)
  • Short circuit to B+/ground or open circuit in the line (Activation Radiator fan control module module)
  • Radiator fan control module Faulty
Lots of warnings there - but to cut to the chase. This is where a Porsche specific diagnostics tool (PIWIS, Durametric, Foxwell, etc.) would be useful. That sort of tool will let you look at the inputs to the module to see if something is triggering the fan (and the module is working OK, something upstream is an issue) and checking the status of Terminal 30 (constant battery voltage). If it was a case of the fan not running - then most of the tools have the ability to tell the module to activate the fan. It also would let you read what temperature the radiator coolant sensor thinks the radiator is at, if that's not working that could cause a false fan trigger.

One thing worth trying (if you have a Porsche capable tool) would be clearing the code on the module and seeing if the behavior continues (and if the code is reset.)

As far as replacing the module - the earlier Cayennes (955/957) had a module that was part of the fan and about unobtainable from other sources (although it was possible that one used on some Ford model was the same..)

I couldn't find the location of the fan control module on a 958 using AllDataDIY... but if you can find it, look for manufacturers' part numbers on it, and google them. While the manufacturer might put the Porsche PN on it - chances are if it's used on multiple vehicles it will also include the manufacturer's own PN, and googling it should turn up alternative sources for it.

Please do post here what the resolution to the issue is..

Good luck!
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