2005 Nissan Altima - engine heating gauge

engine heating gauge goes up to hot and then back to normal engine temperature repeatedly while driving the car. Cannot figure that out. It has not yet over heat or I would notice that… Are the gauges bad or is there a short somewhere in the electrical system.

Did you check the coolant level in the overflow tank and in the radiator? (Note, do not open the radiator when hot, only when the engine has completely cooled down.) I suspect that the coolant level in the radiator is very low, perhaps close to empty, and the temperature gauge pegs out and drops when you are driving because the engine is overheating due to lack of coolant.

Hopefully it is just an external leak, or defective radiator cap, however it might be a head gasket leak. How is the engine running? Any misfire or rough idle, especially when started in the morning?


Check for head gasket. Bubble forms from combustion gases and blocks coolant flow. Then coolant flow overcomes bubble and engine cools again. There is a test kit to uses to check for Gases in the radiator. After that the normal issues like thermostat, hoses, etc.

Sheesh computer substituted gagnes for gases. No idea what they are.