Q: Temperature gauge​ reads a little lower on highway

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When I'm in stop and go traffic my temp gauge sits on the middle but when I am on an open road or highway my gauge goes down from half to a quarter. I've owned more than one Grand Marquis before and it never did this. There is also no check engine light. Is this just a bad thermostat or normal operation?

My car has 131000 miles.
My car has an automatic transmission.

Hi There, It sounds like you may have a faulty thermostat. The thermostat regulates the flow of the coolant in your car’s engine and controls when the coolant flows in and out of the motor from the radiator by opening and closing at specific temperatures. When your thermostat is not working properly or is stuck closed, this will not allow the coolant to properly circulate through the engine, which may cause the engine temperature to fluctuate erratically or in some cases just remain hot. When the thermostat is stuck open it can cause the coolant to circulate constantly resulting in the motor never reaching the correct operating temperature.

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