Does your car’s temperature gauge fluctuate? If yes, then there could be a problem with the cooling system. There are several potential causes for this, so you should be swift to diagnose and fix them before they cause further damage to the engine.
Normally, the needle in a car’s temperature gauge should point somewhere around the center when the engine is warm. However, a slight fluctuation is not something to worry about. But you need to be worried when it points to extreme hot at one time, and extreme cold at the next.
Here are some potential causes of temperature gauge fluctuation and how to fix them.
Slightly-low Coolant level
The coolant level is the first thing you should check if your car shows potential problems in the cooling system. If the coolant level is slightly below the minimum mark in the reservoir, the temperature gauge might indicate too hot only when the vehicle is loaded. It might then recover when off-loaded and display the temperature as normal. This causes the temperature gauge to fluctuate.
The best thing to do here is to top up the coolant to the maximum mark on the coolant reservoir.
The thermostat regulates the flow of coolant into the radiator. If it is not functioning well, it might open or close at the wrong times. The engine temperature will go up if it closes instead of opening, and vice versa.
An old trick to check whether the thermostat is what causes the temperature gauge to fluctuate is to open the radiator cap and start the car on two occasions; when the engine is cold and when slightly hot. If the coolant flows when the engine is cold and does not when hot, then the thermostat is the culprit.
One of the potential causes for a car’s temperature gauge to fluctuate is the Electronic Control Unit (ECU). The ECU interprets the information it receives from the sensors and sends it to the gauges. In this case, the ECU might not correctly interpret the temperature readings from the Coolant Temperature Sensor (CTS), so it sends the wrong readings to the temperature gauge.
The solution to this problem is to have the ECU reprogrammed or replaced.