My check engine light came on. Instead of giving the dealership $115 just to diagnose the problem, Autozone did it for free and came up that either my coolant thermostat is defective or my ECT (engine coolant temperature) sensor is defective. Where does the engine coolant temperature sensor screw in, exactly?

Thanks!

 

I have seen more thermostats go bad than I have the sensors. It could be bad but I would change the tstat just to make sure the engine isn't damaged by lack of coolant flow or lack of cooling capacity if it is stuck open.

 

Might as well change both while you are right there.

 

Thank you both! I'm going to pick up both parts come Monday and then get under the hood. Didn't even think about possible engine damage due to lack of coolant flow or anything all because of a defective thermostat. Again, much appreciated!