I decided today was a good day to tackle changing out the thermostat and the temperature sensor in the M3. I saw where you could do this without having to drain the coolant, and that’s the route I decided to take. I wasn’t fully prepared for just how much coolant was actually going to spill. Oops.
Taking everything apart and putting it back together was pretty straightforward. I think I will replace the o-ring clamps on the intake plenum the next time I have to take it off.
I bled the system and then let the car idle up to temperature where the fan cycled a couple of times. No codes. Once it cools down, I’ll recheck the coolant level.