CATS wrote:I had that same fault and it did not idle high at the time. It is a small sensor to replace, maybe swap with mine for a week or so and check?
CATS
Thanks CATS, but I am going to replace it anyway.
Managed to get hold of the Idling Control Logic programmed in the ECU.
It only considers Coolant Temp, A/C Switch position and Gearlever position. It then works out a target engine idle speed, which is compared to the actual engine speed. The throttle position is then adjusted accordingly.
Easy as that!

I'm going to wait till it acts up again and then try the battery disconnect/ECU reset procedure as per Marius' suggestion.