For a while now my temperature gauge has been reading erratically.

It rises as expected after start up and then later on will suddenly drop to around 55 degrees then either go straight back up to 90 degrees or linger around 60 degrees then return to 90 degrees gradually.

It makes no difference if the heater is on or off and also the outside temp doesn't affect it.

I would guess that it is the sensor but would like to know if anyone thinks it could be the start of something worse.

Yes it is the coolant temperature sensor a common fault on all VAG engines, one of the symptoms is exactly what yours is doing.

Yes CTS is at fault. Buy a genuine VAG CTS, as the cheap aftermarket ones are usually rubbish.

Where is the sensor located? Is it easy to get to?

Take the plastic engine covers off and youll see it just down to the right hand side of the engine, get a new rubber O ring too.

EDIT - if the guage goes up in traffic and down when on the move, quite likely the thermostat may be at fault.

Edited 31 January, 201115 yr by Liverpool-Lad

I had this problem when I bought mine, it was the CTS, get a haynes manual if your unsure. Its only a 2 miniute job

Does anyone have a part number cos I don't have a Skoda Garage nearby so I will have to go to the VW one and they always ask for part numbers.

059 919 501-A

Thanks for your help guys, will give it a go.

Take the plastic engine covers off and youll see it just down to the right hand side of the engine, get a new rubber O ring too.

EDIT - if the guage goes up in traffic and down when on the move, quite likely the thermostat may be at fault.

I made the mistake of getting one off ebay, wish i hadnt bothered, still doing the same thing.

Just ordered a new one, also got thermostat just incase, although its ment to be a 2 hour job, currently looking for a diy guide.