My friend's GP started throwing a P0128 last week, some time after a coolant flush at one of the Valvoline shops (car has 80k or so); Searching here didn't turn up much. According to the snapshot data I gathered with my Tech2, since I cleared the code initially, the car has been driven 133 miles since the first failure, has driven 99 miles since the last failure, and has had four fails, three pass and 7 not run. One person posted in response to another person's P0128 that the thermostat was bad and stuck open, which would make sense; If the thermostat is stuck open or part way open, it would cause the coolant to not heat up as fast as it should tripping the code, but the next person posted "You are so wrong you're right."
. I'm confused. So does he mean he's right that it's the thermostat, or or not? Thoughts?
