RS6 2004

[ortontom]

The fan seems to be on alot, in this weather really? Any suggestions..?

[Dr G]

Could be an electrical fault, failed thermostat, failed temperature sensor somewhere...

[Dr G]

The secondary air pumps can go mad too and sound much the same as one of the rad fans running.

[ortontom]

back on this, yes it sounds like a cooling fan. It goes up in speed too, how to check .....code reader?

[ecain63]

From my days of C5 RS6 ownership, I have bells ringing telling me its a thermostat issue. Worth a look. If it stays on after the car has been turned off for more than a couple of minutes then it's faulty. If it goes off after a minute or so then it might just be hyperactive.