Why is my temperature gauge fluctuating?

The engine in your vehicle runs hot. Very hot. Once running, your engine can reach temperatures up to 220 degrees Fahrenheit! If you’re driving your car and the temperature gauge is stuck on high, low, or going crazy, the issue is most likely with your thermostat. The job of the thermostat is to regulate the movement of coolant in your vehicle and maintain the best temperature for engine operation. As you would expect, the thermostat is heat sensitive and is situated between the engine and radiator. When the engine reaches the right temperature (195-220F depending on vehicle) the thermostat opens to allow coolant to enter and maintain the right amount of heat.

So, what causes the thermostat to fail, causing the gauge to flutter? Let’s start with over and under heating. A thermostat stuck in the open position will allow a constant flow of coolant causing a lower operating temperature. This increases emission, makes the engine wear faster, and leaves your gauge reading cool at all time. On the inverse, an overheating thermostat occurs if the device is closed and won’t open. This will cause the engine to overheat, within minutes this can be catastrophic.

It’s important to note that the thermostat isn’t the only part that can cause a shift in engine temperature. Low coolant, a clogged radiator, bad water pump, and a handful of other things could all be a potential issue. Replacing a thermostat is much easier than replacing an engine, so keep an eye on your temperature gauge. If you notice anything strange, bring your vehicle to an ASE certified auto shop such as Ferber’s Tire and Auto for an inspection.