2008 Polo 1.4 16v high revs when engine cold.

[Team Green]

Hi everyone,
got a bit of a strange issue with our Polo. When the engine is cold the car starts fine and tickover is approx 1000 to 1100rpm and drops down to approx 700rpm within a couple of minutes however I've noticed that come the afternoon on these really hot days the tickover from a cold engine start is 1250rpm!

There are no error codes showing, using VCDS, and the car has done 61,000 miles and servicing is up to date and otherwise runs fine and getting approx 48mpg from it.

I could have understood such high revs when cold in the middle of winter but in this heatwave it just makes no sense. I'm guessing that it's a temp sensor but not sure where to start.

The only thing that has been changed recently is the clutch pedal switch as the revs didn't drop when changing up but this has sorted that problem.

Any help would be appreciated.

Cheers.

[Rob69]

I'd have a look at measuring blocks for temp sender unit output.

[Crasher]

If this is a BUD engine, check the tank vent valve to see if it is made by Valeo, if it is, there is a four digit number dot stamped into the body. If this number is lower than 3109, replace it with 6Q0 906 517