I just replaced my thermostat last night, bled the system, and took the car on a 20 mile shake down with no issues. Driving to work this morning I saw my temperature gauge drop & stay down on the highway, only coming back up to operating temperature in traffic. It seems like my thermostat is stuck open again, meaning the heating element is on constantly, but I’m not sure what fix there is for a bad heating circuit. The connection at the thermostat was dirty, but I can’t imagine a bad connection would allow for the heating element to turn on but not off. I don’t think it’s my water temp sensor, and I’ve got a mechanical fan, and there’s no code. What the hell?