poor mpg, erratic idle speed

[mihaisofti]

My p reg polo 1.4 starts fine, but when it warms up the idle speed takes a long time to settle down to 900 rpm or so. It frequently runs at 2000 rpm without touching the throttle pedal, very slowly returning to 900. This behaviour influences the engine breaking effect, ie little or none.

Also, the fuel consumption seems high, although I don't have a figure for this yet.

Could this be an effect of a faulty coolant temp sensor?

Are there other obvious causes of these symptoms?

Any help with this would be much appreciated.

Mihai

[anilkumar]

when was car last servied

you may need a idle control valve or the throtle body may need cleaning or a sensor may need to be replaced