thermostat

[refueler]

I installed a new thermostat about three weeks ago it worked until this past weekend and now the coolant gauge stays on cold.My question is does the thermostat open by the coolant temperature at the thermostat or does the ECU control the thermostat's opening by using the information from the two coolant temperature sensors. I've read somewhere that the thermostat can be opened by the ECU and there is an electrical connection on the thermostat. Since my coolant gauge only goes up while the car is idling I think that the thermostat is stuck open.

[walky_talky20]

Check the codes first. If there is a cooling system fault stored, the ECU will make it run cold.

[Gooner1886]

Change your ECT sensor.

[customa4]

A lot of good info in this three on testing your thermostat. Click Does the temp gauge ever move or it always stays cold?