I've got a 98 Tacoma 4x4 with the 2.7l 4cyl. I recently got a cel and scanned it and came up with P0125. The code comes back as "Insufficient Coolant Temperature for Closed Loop Fuel Control." I was thinking that maybe the engine coolant temp sensor was bad. The Haynes manual says its located on the back of the head, but I can't seem to find it if it is. There is a very small sensor screwed into the top of the water neck where the thermostat goes. I was wondering if anyone can verify the location of the ECT and what the sensor in the water neck is. Any help would be much appreciated.

Thanks,
Terry

 

If you get a Haynes manual and look at the wiring diagram you can probably get both the location of the sensor and the wiring diagram for the ECU to ensure that if the sensor is in fact good, that the signal is reaching the ECU as well. Sometimes (although rarely) a wire can become broken or corroded causing the sensor to seem bad.