Updated at: 20-07-2022 - By: Lucas

Drivers may notice that the coolant/antifreeze temperature gauge in their automobile is permanently set to a low or nonexistent reading.

If you find yourself in this situation, keep in mind that the engine’s cooling system operates at a consistent temperature while it’s hot. With this coolant, the engine’s performance can be maximized.

There are many reasons why the temperature gauge on the coolant may not work properly over time, and we’ll go over them in the following paragraphs.

The role of the cooling temp gauge

Temperature Gauge Not Working

It is critical that you first understand the purpose of this gauge, as it will make it much easier for you to discover its function and how it functions.

As a result, temperature measuring equipment varies per model of vehicle. It is common to see a coolant temperature sensor with two wires that go directly to the cluster in older vehicles.

Because antique cars don’t have a motor control unit like new cars have, the control unit that uses the temperature of the cooling agent as information, this can be accomplished.

Modern automobiles are equipped with an engine control unit (ECU), which uses coolant temperature information to determine how much fuel is needed at all times.

It’s critical to realize that the wire from the cooling agent’s temperature sensor may first go to the engine’s control unit before being routed to the instrument cluster.

In some cars, such as those made by Asian manufacturers such as Nissan, the coolant temperature sensor is used for both the immediate gauge and the control unit.

Four-wire temperature sensors are common, and they serve as a direct link between the engine’s control unit and the instrument cluster.

There are many reasons why the engine temperature indicator lingers at a low level, and we’ll explain them below.

In the following paragraphs, we’ll examine the most prevalent and less common explanations.

1. Bad coolant temperature sensor

The coolant temperature sensor is the most prevalent culprit in poor engine temperature readings because it feeds incorrect data to the instrument cluster.

2. Faulty cluster

Another possibility is that the temperature gauge in the vehicle is malfunctioning. Even so, modern cars have a variety of temperature sensors built into the instrument cluster, and in some cases, the temperature gauge can be replaced or any flaws discovered can be corrected.

The group of instruments may need to be replaced in some cases; in these cases, dealing with specialists will ensure that everything is done according to plan.

3. Broken cables to sensor or gauge

Temperature Gauge Not Working-2

In this article, I mentioned that the wires go from the sensor to either the cluster or the motor control unit, so be sure to check for any broken cables along the way..

Multimeter testing from all wires is the most basic solution. You don’t need to be a mechanic to utilize this highly vital tool, but you do need some knowledge of the car and electronics.

Otherwise, you should get the vehicle serviced by a qualified workshop or mechanic.

4. Bad thermostat

The thermostat’s job is to limit the amount of coolant that can pass through the radiator. If the thermostat is left open, it is highly likely that the temperature will not reach an ideal level.

A more aggressive driving style will cause a little rise in engine heat under these circumstances. If the thermostat’s temperature gauge steadily increases, it’s most likely that the thermostat is malfunctioning.

5. Corrosion between connectors

Corrosion between the connectors is another possibility. The sensor connector, as well as the cluster connector and the motor control unit connector, must be thoroughly cleaned and sprayed with the electronic cleaning equipment in this situation.

If corrosion is present, the seals of the connectors are likely to fail in certain areas. This may necessitate checking the connectors to see if they need to be repaired, if necessary.

6. The presence of air in the cooling system

As a last consideration, it’s crucial to note that if air is present in a car’s cooling system, it can cause the temperature sensor to remain chilly.

Draining the cooling system is critical if there is or you fear there will be air in the system of the car.

7. A bad electronic control unit (ECU)

The car’s control unit may be destroyed over time and for various reasons if temperature data first reaches the ECM, which then sends the data to the cluster.

To see if the engine control unit is receiving temperature data, run an error code check if necessary. To do this, you’ll need an OBD2 scanner.

Checking the sensor used by both components is critical if the temperature control unit sits in the engine control unit but not in the control group.

To do this, the temperature output from the engine control unit must be measured, and this should be done by an expert in car electronics.

If the engine control unit is not broken, it is not required to replace it because this component is expensive and requires coding.


As a result, if you notice that the coolant temperature gauge is reading low or is not working, the first thing you should do is verify that this indication is functioning properly. To avoid paying for labor at an auto shop, simply follow the instructions provided in this article.