Car Running Hot but Not Overheating| Why is Your Car Temperature Gauge High But Car Not Overheating?

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Is your car running hot but not overheating? I will show you why your Car temperature gauge goes up and down and no heat

Every car is manufactured with different gauges on the dash that serves different purposes and informs you about the essential things of your car.

The fuel gauge informs you how much gas you have left so you don’t run out.

However, the importance of gauges like engine temperature gauge can be complex to understand.

Car Running Hot but Not Overheating| Why is Your Car Temperature Gauge High But Car Not Overheating?

This article explains the importance of the temperature gauge and why the car isn’t overheating when they are reading high.

Basically, we would be discussing the reasons why you might be getting a false reading.

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Temperature Gauge High But Car Not Overheating

The temperature gauge helps regulate the hotness of your engine and informs you. Under normal circumstances, your temperature gauge should read around the middle, indicating that your engine isn’t too hot or too cold. But it can be a major issue if the temperature of your engine gets excessively hot. Overheating can cause the seals of your engine to break or the head can crack.

Sometimes, the temperature gauge works appropriately, and high reading can mean the engine is overheating. However, the gauge can mess things up in some cases.

What Can Cause My Temperature Gauge to be Reading High?

Reason for a car running hot but not overheating

Your temperature gauge may be reading high but not overheating sometimes due to some common factors. The common causes of a high-temperature reading are:

  1. Failed Temperature Sensor
  2. Broken Temperature Gauge
  3. Low Coolant or Air in System
  4. Head Gasket Failure
  5. Faulty Water Pump

1. Failed Temperature Sensor

The temperature sensor helps measure the temperature of the engine. You may be getting a false reading if the temperature gauge is giving a high reading when the engine is not overheating. This means that the temperature sensor may have malfunctioned or have been failing.

A damaged sensor may not be sending out reading, and the car could instead respond by sending out a false high-temperature gauge reading instead of an accurate one.

The sensor could get impaired while driving if something hit it or if it has debris on it. Also, another thing that can cause the sensor to get damaged is if the wires are damaged. If you get a false high-temperature reading, clean and check your temperature sensor.

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2. Broken Temperature Gauge

Your engine can read as though it is overheating when there’s a broken temperature gauge. The temperature gauge consists of moving parts which are prone to breaking.

The needle of the temperature gauge can break if:

  • it gets stuck in the hot section and breaks
  • grease causes it to stick
  • one of the stepper gears in the gauge gets broken.

The gauge has different gears that helps move the needle. These gears can wear as time goes by and if one breaks then the needle may move incorrectly thereby giving a false high reading.

3. Low Coolant or Air in System

Your temperature gauge may read hot if the engine is really overheating. A low coolant or air in the system may be the most common reason for this. You have to ensure that your engine really is not overheating if your gauge is reading hot. Ensure you have coolant and make sure air didn’t get in the system if you changed or coolant.

4. Head Gasket Failure

The head gasket is responsible for sealing the coolant, combustion chamber, and engine oil pass. Your car temperature gauge may increase if you have a faulty head gasket. Head gasket is a vital component of your car engine since it forms a seal between the engine block and cylinder head. So, any damage to the head gasket can lead to severe issues with your car.

5. Faulty Water Pump

The water pump is a vital component of the car’s cooling system. The water pump helps to push the coolant throughout the cooling system. The water pump can breakdown causing improper coolant flow.

The water pump can malfunction for a number of reasons. They include:

  • shaft breakage
  • seal leakage
  • casting breakage


What to do When Temperature Gauge is High but Car Not Overheating?

What are you supposed to do if your engine is not overheating, but you keep getting a high-temperature gauge reading?

As we mentioned earlier, check your temperature sensor and ensure it is clean and working properly. Check the fuses too to ensure none is disconnected. Proceed to check the mechanical parts of the temperature gauge if the temperature sensor is working well.

Secondly, ensure the needle inside the temperature gauge isn’t broken or stuck and that all the moving parts are clean.

Then ensure the coolant or air in the system is blowing properly.

How to Fix Car When Temperature Gauge Goes Up and Down and no heat

If the temperature gauge of your car is in the middle while driving, this may indicate a problem since the gauge should be between the cold and midway mark. You may start to notice it moving towards the red on the gauge but then drop back to the midways.

The car temperature gauge of your car going up and down may be caused by a sticky thermostat or possibly a cooling fan that may be functioning irregularly. The thermostat controls the flow of the coolant in the engine of your car.  When your thermostat is not functioning properly or is stuck closed, it will prevent the coolant from flowing accurately through the engine. This can cause the engine temperature to alter or just remain hot. When the thermostat is stuck open, the coolant can circulate regularly causing in the motor not to attain the correct operating temperature.

A defective cooling fan relay or resistor may be responsible for the cooling fans working irregularly. The relay controls the power to the fan, meaning if it’s not working well, the fan may come on randomly, stay on at all times, or may not come on at all. On the other hand, the resistor controls the stages at which the fans come on.

If the Temperature Gauge Goes Up and Down and No heat

There may be several reasons causing your temperature gauge to fluctuate or go up and down. The possible reasons include:

  • Low coolant level delaying thermostat opening and closing
  • A partially clogged radiator
  • Air pockets in the cooling system
  • A loose drive belt that fails to operate the water pump correctly
  • A short, or loose or corroded connectors or wires, in the electrical circuit for the sending unit or gauge
  • Cooling fan or relay problems
  • A coolant leak
  • Faulty thermostat
  • Bad temperature gauge
  • A water pump with a loose impeller
  • Blown head gasket

How to Fix Car When Car temperature gauge goes up and down

To fix this problem, you may need to consult your vehicle manual to locate wires and components. You may need to ground the wire that connects to the temperature sending unit and grounding the wire can damage the temperature gauge in some cases.

  1. You need to first check for diagnostic trouble codes (DTC) if the check engine light is on. The codes may point to the source of the problem.
  2. It is important to turn the ignition switch off before unplugging wires.
  3. Then turn the ignition switch On to check gauge or warning light response, to prevent damage to the computer.
  4. Then turn the ignition switch “Off” and unplug the sending unit electrical connector.
  5. Then turn the ignition switch “On”.
  6. After doing the steps above, the gauge should indicate cold whether the engine is warmed up or cool.
  7. Using a jumper wire, ground the signal wire, then turn the ignition switch “On”. The gauge should read “hot”.
  8. The sending unit may be bad if the temperature gauge responds, but not when connected to the sending unit.
  9. You should unplug the wire at the temperature gauge if the gauge indicates higher than “cold” when you unplug the sending unit. If the reading of the gauge is “cold,” the wire is shorted.
  10. If the gauge still states higher than “cold,” you may need to replace the gauge.
  11. If the gauge fails to indicate “hot” when the wire is grounded, check the circuit fuse again. Then ground the gauge terminal where the wire connects to if it indicates everything is okay.
  12. If the gauge indicates “hot,” then you may have to check the wire for damage.


From the three main reasons why your temperature gauge may be high when your car isn’t overheating, the most common reason for an overheating engine is lack of coolant or air in the system.

If you are getting high readings when your engine isn’t overheating, then check the temperature sensor and mechanical part of the temperature gauge. If your engine is still overheating, then you need to get it checked out by a professional mechanic to prevent major damage to your vehicle.

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