Fix P0128 temperature gauge dead – GM vehicles
If you get a P0128 code AND the temperature gauge is dead, head right for the thermostat. When a thermostat goes bad on a GM vehicle, the PCM sets a P0128 trouble code and commands the cooling fans to run and disables the temperature gauge. Don’t waste time trying to fix the gauge. First, replace the thermostat. If the gauge still doesn’t work, then you can start diagnosing that problem after you’ve cleared the P0128 code.
© 2012 Rick Muscoplat