little help
 

my 02 lightning is throwing obd2 code p0125 Insufficient Coolant Temperature for Closed Loop Fuel Control. I changed the thermostat for a new one still throws the same code. from what i have read it is either and ECT sensor (engine coolant temp) or CHT (Cylinder head temp sensor). my gauge shows that the temperature is fine so i think i need to change whichever sensor doesn't control the gauge since it reads correctly. does anyone know which sensor controls the gauge or has anyone came across this before?

thanks

Those codes tend to be more common in the cold months on cars with lower temp thermostats and lower fan settings. It's not necessarily a sign of a bad sensor. The PCM is looking for a minimum threshold to be reached, sometimes there is also a time window involved, and if the engine is slow to come up to temperature, you can sometimes get a code.

This may be a potential explanation if all systems seem to check out.

my stat isn't cold it is 190. my fan settings are stock and my engine heats up fast. i appreciate the feedback though. i had the code deleted and went into walmart for a short time. when i came out it threw the code again right away and the engine was still warm at that point. that is what is also making me lean to a bad sensor but i could be wrong.

But you may be right!

we have a CHT not ECT...located in driver side head, inboard (under lower intake manifold) between cylinder 5/6,

Wait longer on a cold start before driving, or dont beat on it while its cold is the translation for that code. The gauge reads off the sensor you suspect is bad, if the sensor is bad, the gauge wouldn't read. (BTW its a PITA to change that sensor with the lower intake, alternator and pulley bridge still on)

Check and make 100% positive your T stat is what you say it is. Factory is 180.

i drive it hard rarely, especially since it is all stock. i usually let it warm up but sometimes not. i have gotten it off an on over the years last time i changed the thermostat and it went away for a couple of years plus my gauge read low all the time i knew that one was bad. i don't think this one was bad but i changed it just to see. it is a superstat i got from advance i will recheck the temp on it. thanks

turns out it wasn't the same code again. it was a different one all together that had nothing to do with coolant. thanks again