0 reading temperature gauge STILL after new thermostat and ECT

[Tilly2025]

2018 Yukon Denali had CEL and temp gauge read 0. Replaced the ECT and thermostat today, no change.

It’s been like this for a week. There iwas one day when it worked again before the new parts.

Bonus issues—getting a rumble strip feeling when accelerating around 1200 rpm. Have an appointment scheduled. Torque converter?

 

[L8T BURB]

You've got a stored code for "coolant temp below threshold". This code is what causes the temp gauge to drop to 0 and the other fail safe modes to activate. You will need to get that code cleared before things will work. If you don't have a pocket scanner or similar to clear the code yourself, I believe you can disconnect the battery for 30 minutes or so and it may clear it.

 

[Bagherra]

Same issue here, just replaced the ECT sensor 2 days ago and temp dropped to 0.

Thought i cleared the code but i guess i didnt.

 

[L8T BURB]

Same issue here, just replaced the ECT sensor 2 days ago and temp dropped to 0.

Thought i cleared the code but i guess i didnt.

If your temp dropped to 0, the root cause is a faulty thermostat. If you haven't replaced the thermostat yet, clearing the stored code will only temporarily work. The lasting fix is replacing the thermostat and then clearing the stored codes.

 

[Tilly2025]

To update yesterday the gauge started working properly and today the CEL is no long on.