Because it is not securely fastened.
The gauge does not cause the heat; it only shows what it is.
Idle the engine, remove the temp sensor wire on the engine and ground it. If the gauge does not move one can assume it has failed.
replace temperature gauge
Fuse location for temperature gauge for a Malibu
Yes, they move slowly but constantly. Faster during earthquakes.
Defective temperature gauge or defective temperature sensor?
The temperature gauge sending unit might be bad. To check it find the sending unit on the side of the engine block (on most models) and pull the wire off and ground it with a piece of wire and have someone look at the gauge to see if it moves.
Bad gauge or defective coolant temperature sensor
why is the temperature gauge not moving on a 2007 Lincoln mkz
Why does your temperature gauge rise and lower only when you have the heat on?
The thermometer that reads your engine temperature, I presume, is damaged or broken. Without the gauge to tell your fan how hot your engine is it will keep running as a 'better be safe then sorry' feature.
If the temperature gauge in your 2004 Grand Marquis isn't moving, it could be due to a faulty thermostat, which may be stuck open, preventing the engine from reaching the proper operating temperature. Another possibility is a malfunctioning temperature sensor or gauge itself. Additionally, check for issues like low coolant levels or a blown fuse affecting the gauge. It's best to have a professional diagnose the issue to ensure accurate repairs.