Mil p0125



I have a 2000 Toyota Tacoma 2.4L. with 115,000 miles on it. The MIL is on. I got a code of (P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control).

I’ve replaced the thermostat and cleared the code…same code came back after about 2 miles of driving. I have not noticed any drivability issues. The temp gauge is where it normally is.

1 How can I (is it possible to) test the coolant temp sensor with my multimeter? If so, what is the procedure.

2 I’d also like to know how to test the O2 sensors,

3 If the coolant temp sensor and the O2 sensors check out what is the next most likely cause of the MIL being on?

Any assistance you could provide would be greatly appreciated.



PS, love the show


Yes, you can test the engine temperature sensor with a multimeter. You can check it hot. You can check it when the engine is any temperature. All of the “How-to” is in the Haynes repair manual for your PARTICULAR year and model. NOT the “big book”!