Just had my octavia 2.0 pd 140 estate for a couple of weeks and no problems until today. When the engine was turned off there was a whirring noise under the plastic engine cover that carried on for about 10 secs and then switched itself off. When I switch on the ignition it starts again and carries on when the engine is started. The cooling fan is not moving. Any ideas would be greatly appreciated.

If it is continuing after the engine is turned off you can rule out belts and pulley's.

You say the fan isn't spinning when its making the noise?

There are a few different valves and sensors that make some strange noises just before or after the ignition is turned on/off.

Is it a new noise that you've not noticed before?

Thanks for the reply. It is a new noise that starts when the ignition is switched on and carries on when engine is running. It only stops 10 to15seconds after the ignition is switched off. The fan is not moving.

Could this be the EGR vavle ?

Problem resolved by fitting a new throttle body. Chose to go for an original VAG part which was not cheap but at least the problem is now fixed. Thanks for your ideas.