I'm trying to test my ECT. I have been getting error code P0125. I replaced the Thermostat. I added coolent to level. This code seems to clear on its own when I do short hop driving. However, if I do long haul driving where the car heats up, the light comes on.

I measured the resistance on the ECT and for the most part it was no resistance but this was with the car up to temp. Anybody know what the resistance should be at ambient temperature and what it should be when up to temperature...the acceptable ranges?

I thought it was the fan, but I turned the air conditioner full at idle and the fan is coming on.