Suddenly no hot air out of heater and red hot engine indicator. First steady and showing on and off in first 5 or so miles. Code set is P0117 " "Engine Coolant Temperature (ECT) Sensor Circuit Low Output Problem". Could be several things, but what is your experience with this and how should I approach this? Thermostat? Water Pump? Most common reason?
Don't thermostats usually fail open? You notice it when the engine is running cold. Not sure how you check for ICE electric coolant pump function. Not familiar with the code either. I'm a lot of help.. .
Have you ever swapped out the pump or thermostat? I did our 2010’s when it had 180k miles on it and I noticed some building resistance in the motion of the impeller. Is the engine coolant level stable? Good luck and keep us posted .