Why is my Temperature Gauge not Going Up?

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As an automobile owner, it is important to make sure that your car is running in the best condition possible. You do this by keeping an eye on both internal and external components from the wide variety of gauges and sensors providing information on the dashboard. One of the most important aspects of keeping your car running well is making sure that the temperature gauge is reading accurately so that you know if your engine is getting too hot.

However, if your temperature gauge isn’t going up when the car’s engine is getting too hot, then you have a problem. If it is not, you could end up with some very costly problems down the road. An overheating engine can lead to a blown head gasket, warped cylinder head, and other expensive damage. 

Now to the problem at hand. You notice that the engine is visibly hot but the needle appears to be right on the far blue side of the gauge – indicating that the engine is not hot in the slightest. Perhaps not even warm. So, you get out to investigate the engine yourself and see that it is scalding hot. This should tell you that the temperature gauge is not working. 

Well not to worry, at least you noticed right on time and didn’t end up with a smoking engine. But what could be the problem? There are a few things possible reasons that could be causing your temperature gauge to not work. We’ll take a look at some of the most common reasons in this article. 

7 Reasons Why Temperature Gauge Is Not Going Up

Reasons Why Temperature Gauge Is Not Going Up
Why is my Temperature Gauge not Going Up?

The following are the most common reasons for a temperature gauge not going up despite you noticing and having verified that the engine is running hot:

1. Faulty Engine Coolant Temperature Sensor

A clear and common reason that resorts to first for a temperature gauge not going up is a faulty engine coolant temperature sensor. The sensor is responsible for measuring the actual engine coolant temperature and sending this information to the gauge on the dashboard. 

The ECU then uses this data to control the fans, ignition timing, and other important engine functions. If the sensor is not working or in some rare cases not calibrated correctly, it can result in an inaccurate reading on the gauge. In some cases, it may even cause the gauge to give a false reading of a cold engine when the engine is actually hot. 

Also Read: How to tell if your Coolant Temp Sensor is Bad

2. Broken Wirings

Another very common reason for a temperature gauge not going up is broken wiring or harness. This can be caused by various things such as accidents, natural wear, and tear, or even rodents chewing on the wires. 

The wiring runs from the sensor to the gauge on the dashboard and if it is broken, then the information will not reach the gauge. The result is an inaccurate or completely false reading on the temperature gauge. 

3. Faulty Gauge/Cluster

Although it is not as common as a faulty engine coolant sensor or broken wiring, there are occasions when the gauge or cluster itself may be at fault. The gauge or cluster is the component that actually displays the information from the sensors on the dashboard. 

If there is an issue with the gauge or cluster itself, then it will most likely need to be replaced.

4. Corrosion in plug connectors

Over time, the connectors that plug into the sensor and gauge can become corroded. This happens when the connector is exposed to moisture and the elements. The corrosion can cause a poor connection between the sensor and gauge, which will then result in an inaccurate reading on the temperature gauge. If this is the case, then cleaning the corrosion and using dielectric grease may solve the problem or by just simply replace the connectors.

5. Bad Thermostat

A thermostat is a temperature-sensitive valve that regulates the flow of coolant to the engine. It is responsible for keeping the engine at the correct temperature by opening and closing as needed. 

If the thermostat is not working properly, it can cause the engine to run too hot or too cold. This will then result in an inaccurate reading on the temperature gauge.

6. Air in the Cooling system

If there is an air bubble right at the sensor spot, it will give an inaccurate reading on the gauge. This is because the air bubble will not let the sensor get a proper reading of the engine coolant temperature. 

One way to try and fix this is to bleed the cooling system. This is done by opening up the bleeder screw on the thermostat housing and letting any built-up air escape by releasing the pressure from the radiator cap. 

Also Read: Why Does My Car Overheats when AC is On

7. Broken Engine Control Unit

Rare but it does happen, a broken engine control unit can also be the reason for a temperature gauge not going up. The engine control unit is responsible for receiving and sending all the data from the various sensors in the car to the appropriate component. In addition to the temperature gauge, it also controls things like ignition timing, fuel injection, and more. 

If the engine control unit is broken, then you may see more than just an inaccurate reading on the temperature gauge. You may also experience problems with starting the car, or even engine failure. 

How a Temperature Gauge or Warning Light Works

How a Temperature Gauge or Warning Light Works
Why is my Temperature Gauge not Going Up?

A temperature gauge usually has a sender unit that is screwed into the radiator or water outlet. The sender unit has a contact arm, which completes the circuit when it’s immersed in coolant. The resistance of the contact arm varies according to the temperature of the coolant. This resistance alters the current flowing through the gauge and so, by means of a calibrated dial, we can read off the engine temperature.

Some cars have warning lights that come on when the engine reaches a certain temperature. These work in a similar way to temperature gauges but use light-emitting diodes (LEDs) instead of a gauge.


How long should a car take to reach operating temp?

This depends on many multiple external and internal factors including the weather, vehicle and fuel type, speed, and driving habits. But as a general rule, most engines should be at their optimal operating temperature within 10 to 15 minutes. The more strain you place on the engine, the quicker the engine will heat up. Obviously, if the temperature is extremely cold outside, the engine will take longer to reach its optimal temperature. 

How do you tell if a thermostat is bad in a car?

To tell if the thermostat is bad, you need to inspect it and test it. The thermostat is a cylindrical-shaped metal part with a small spring. It is located on the lower front part of the engine, near the water pump. To test it, remove it from the engine and immerse it in a pot of boiling water. You can also test the thermostat by checking its resistance with a multimeter. The normal resistance range for a thermostat is 80 to 120 ohms. Anything outside of this range may indicate a bad thermostat. 

How do I know if my coolant is circulating?

You can simply tell if the coolant is circulating by checking to see if the radiator fan is running. The fan should come on when the engine reaches its optimal operating temperature. If the fan is not running, then there may be a problem with the fan, wiring, or switch. You can also check to see if the coolant is circulating by feeling the upper radiator hose. If it is hot, then the coolant is circulating. If it is cold, then the coolant is not circulating.

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So, if you’re car’s temperature gauge isn’t going up, it’s most likely one of the seven issues mentioned in this article. Do some troubleshooting and see which one is causing the problem. And don’t forget to take your car to a mechanic if you’re not comfortable doing it yourself. Thanks for reading!

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