bad o2 sensors

I have code 0125 on 97 2.4 and have changed the ect and thermostat and still have code. Will o2 sensors set this code and how much will it effect my mpg.

 

The P0125 is a common code that gets misdiagnosed on the Toyota. If you have already changed the thermostat and the ECT (which is located on the back of the head, not the one on the side) then you are most likely looking at the O2 sensor located before the catalytic converter.

 

Thanks Bill but where is the 2nd ect located on head. I changed the one on the side.
Thanks travelcarp

 

Personally, I look at changing out the O2 sensor(s) every 100k or so; you're lucky if you can go much longer than that. Oh ya, Bill, you ROCK!