I've been having an annoying problem with my sti ra V2 if it's left sitting for a day without being started or driven.

When I try to start the car, it won't fire up, as if I've flooded it. The 'check engine' light then appears and the car goes into safe mode (whirring fan etc). It will then start ok, but stays in safe mode until I reset the ecu.

Once the car is up to temperature after resetting the ecu, the problem disappears, even after turning the engine off and back on, or leaving it for a while then returning to it and starting it.

I've pulled off an error code 21 from the ecu, which tells me the problem lies with the 'Engine Coolant Temperature Sensor'.

Any words of wisdom?

 

replace it, 5 min job,sensor is about £20 iirc.
Located in the block (whilst looking at the engine) by cylinder no 3 (the one nearest the turbo).
Should be orangey/brown.

 

Thanks buddy, will get one ordered up tomorrow.