My car throws a P0128 code every so often. After a while the code will go away, but it will pop up again. I suspect the thermostat is stuck open or the temp sensor is bad. Is there a way to diagnose the problem?
The chapter has some specialized tools right? Is there one of those laser temp sensors I can borrow? I can run the car for a while and measure the temperature. If it throws a code but the temperature is in range then I'll know its the sensor.