A4 car self revving on ignition! any ideas?

[hjervis]

Hi there,

Our A4 TDI Avant X reg(2000) is intermittently revving itself when the car is started. The first time I thought it must have been my foot on the accelerator ( it sounds like you've pressed your foot to the floor and then straight off again), but on the second/third/fourth time this was definately not the case. I've had a search through the forums and can't see anything. I've got a funny feeling that this is going to be down to a'sensor' somewhere but if anyone has any ideas it would be much appreciated!

[activa]

I had this a while back and was told to replace the water temperature sender.

Hasn't done it since so I can only assume it was faulty.

Cost about 27 quid for a diesel Golf,so I can see the price being similar for your car.

[CabGirl]

I had this a few times on my old cab '95 when the battery was left to go flat. Two weeks was the max I could leave it without driving it...

I don't know if yours is the same but on mine it settled down once the auto box learned my driving style again.

[TDiAvant]

Sounds like a MAF fault.

[TheSaint]

Sounds similar to a problem I had on my TDI a while back which turned out to be a coolant sensor. Effectively, the engine management system kept thinking the car was cold so revved the engine to get some heat in it.

If it's intermittent, then a diagnostic should find it pretty easily. If it is a coolant sensor, word of warning, keep an eye on the coolant level - shouldn't change but you don't want the thing overheating. Also, if you get a stealer to do it, it involves draining some of the coolant away. Double check that they put it back in. Vindis Audi didn't in mine and I only noticed because I always check everything after its been in as I don't trust garages.