mason110

Comes back as a coolant sensor malfunction. Anyone have any ideads why it would throw this code? T-stat is only a few months old, and is 160*. Never had a problem with it throwing a code. Now that winter came to new york, and has been cold I have been throwing this code for eh two months or so. Thanks in advance for any input.

Archangel79

I had that problem after I swapped to a colder T-stat in my '04 Impala. It was supercharged and I was doing some mods...one of the main supporting mods is a colder T-stat. I used to get P0128 regularly when it was cold out. Basically what is happening is that your engine is not warming up fast enough for the computer.

The PCM is programmed to expect the coolant temp to reach XXX*F in a certain amount of time. If that doesn't happen then it throws a code because it thinks there's a problem.

Judging by your mod list, and seeing your E-fans and the nitrous I assume you have a tune. At the least I'm guessing you have the PCM programmed for the E-fans to work with your colder thermostat. That would most likely be the cause of your problem. If you want it to go away, just swap the stock T-stat in until it warms back up. It worked for me.

- Jason

mason110

Right, yeah I do have a tuned pcm, ill give it a try. Thank you.

Archangel79

You bet.