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HomeTips & GuidesHow to Test a Temperature Gauge: A Guide on Keeping a Healthy Temperature Gauge

How to Test a Temperature Gauge: A Guide on Keeping a Healthy Temperature Gauge

Learn how to test a temperature gauge from this detailed guide. We understand that your car means a lot to you. Hence, frequent damages caused by excessive engine temperatures can cost you heavily. 

Here’s where a temperature gauge comes in handy.

 The device helps you keep track of the ambient car engine temperatures at all times.

 But sometimes, it may fail to work for various reasons we’ll list. 

The guide also covers the procedure for testing if the gauge is in good working shape. 

Table of Contents

What is a Temperature Gauge?

It is a device that tracks your car’s engine’s temperatures by monitoring its coolant temperatures. 

The gauge helps you know when the vehicle’s operating temperatures are out of the safe range. 

It alerts you, thus assisting the driver to take the proper corrective action to prevent engine damage. There are different forms of this device depending on the car type. These include: 

  • A mechanical dial temperature gauge
  • Digital display system 
  • Simple warning lights 

Other types of these devices perform additional actions, such as providing the cabin air temperature.

 In advanced vehicles, a temperature gauge also has a fuel economy meter and an oil pressure indicator. 

How Does the Temperature Gauge Work?

A needle pointer temperature gauge. 

A needle pointer temperature gauge. 

The gauge typically keeps track of the engine coolant temperatures. Hence, it helps you know when it’s too hot, and you need to pull over for some cooling. 

Normally, the car engine’s coolant circulates over the engine chamber.

 Its fundamental role is to pick up the high heat generated from the car’s fuel combustion and cylinder movements. 

Next, the coolant dissipates the heat to the surroundings via the radiator. 

So a temperature gauge is a component with a sensor in the car’s thermostat that reads the current coolant temperatures. 

It then converts the temperature to an electrical signal and a digital/analog display on the dashboard. 

The sensor takes the coolant readings every time you’re driving. Then the temperature readings keep shifting as you drive. 

Common Problems That Can Occur with a Temperature Gauge

A Car Temperature gauge on the dashboard. 

A Car Temperature gauge on the dashboard. 

Why would a car temperature gauge signal high temperatures/erratic readings? Below are some of the reasons. 

Damaged Wiring

If there’s a fault in the vehicle’s wiring, the temperature gauge may provide out-of-range measurements.

 If this fault is a wiring break, the indicator will give no reading at all. 

Clogged Coolant Terminal

Checking a car radiator. 

Checking a car radiator. 

The coolant can sometimes have materials that derail its normal movement around the engine. 

These can range from dirt particles to large debris. If they exist, then it means the smooth movement of the coolant will be no more. 

Consequently, the coolant will not excellently cool the engine, thus resulting in heat accumulation. Hence, the gauge will display a high-temperature reading. 

Sensor Malfunction

The temperature levels sensor is among the most essential components of a gauge. 

Hence, if it’s not working, it’ll display the wrong figures. It can be very dangerous, primarily if it reports a lower temperature than normal. 

The engine will overheat, leading to a shutdown if there’s no mitigation measure. 

Damaged Water Pump/ Blocked Radiator

A Car Radiator. 

A Car Radiator. 

Water’s the typical cooler in cars. It is pumped from its chamber around the engine chamber for cooling. 

So when the pump fails, then the coolant won’t flow. The temperature gauge will thus show the wrong figures, leading to overheating. 

The same issue will occur if the radiator is not functional. 

Low Coolant Levels

Finally, the engine will not cool appropriately if the coolant is below the right levels. 

Thus, you must always check out the level of coolant. Also, conduct regular wiring inspections and confirm no debris in the coolant. 

How to Test a Temperature Gauge with a Multimeter

Testing with a multimeter. 

Testing with a multimeter. 

  • Primarily ensure you are safe. So switch off the car’s electrical system by first switching the ignition off if the vehicle is running. Next, disconnect the battery from its terminals.
  • Pick out the temperature sensor. You’ll likely find it in the engine block. But if you can’t access it, you can have a mechanic identify it for you. 
  • Remove the sensor’s electrical connector to begin the testing process. You don’t need a sophisticated tool for a successful test. A simple multimeter is enough. 
  • Set the multimeter in the 10 kΩ mode, then connect its testers to the ends of the temperature sensor. 
  • If the sensor operates normally, the multimeter will return an OL signal. It means there’s an open circuit, and thus, the electrical system is working appropriately. But if it doesn’t return the signal, then there’s a high chance it is malfunctioning. 
  • Next, warm the sensor with a hairdryer. Now set the multimeter into the 0.2kΩ and 1 kΩ range, place the testers again on it, and check if it’s working. 
  • If you don’t get a reading, your sensor is faulty, and you must replace it. So install a similar sensor with the same ratings, put the electrical connectors and the battery in place, and then test it. 
  • The temperature gauge should now work excellently if the sensor is the issue. 

How to Fix Your Car’s Temperature Gauge

Replacing a Faulty Thermostat

A professional mechanic with a car thermostat. 

A professional mechanic with a car thermostat. 

A bad thermostat will affect the entire engine temperature detection system. So fix it immediately if the device fails via the following quick steps. 

  • Cool the car’s coolant by switching the engine off if it is running. This step should take about twenty minutes. 
  • Next, find out where the car’s thermostat is located and drain the water from the radiator. Remove the thermostat from its chamber and place it in hot water to test if it works. If it doesn’t respond to the hot water, it is faulty, and you should replace it. 
  • Hence, install a new thermostat, and fill the coolant with a new batch of cold, clean water. Replace the radiator cap and start the car. 
  • The thermostat was the issue if the temperature gauge reads reasonable readings now. 

Diagnosing Air in the Coolant System

Fixing an automobile thermostat. 

Fixing an automobile thermostat. 

The coolant system’s radiator hoses shouldn’t have air in them as it can lead to wrong temperature sensor readings.

 Your car’s cooling efficiency will also significantly dip with air in the sensor/thermostat. 

Here’s the process to diagnose and remove air. 

  • Uplift the car’s front side by placing a jack beneath and applying its lever to lift it. 
  • Remove the radiator cap and ignite the car to move the coolant. It will help expel the air trapped in the radiator. 
  • Return the car to its original position by lowering the jack, then fill up the radiator with a coolant and test it. 

Diagnosing a Faulty Instrument Cluster

The underlying car issue may be the instrument cluster. 

So if none of the issues we’ve highlighted above is present, then the only diagnostic measure is of the cluster. 

Check out if there’s an underlying issue with the gauge cluster. 

How Much Does a Temp Gauge Repair Cost?

A Simple Temperature Gauge. 

A Simple Temperature Gauge. 

The cost of repairing your temperature gauge will primarily depend on its particular problem. 

For instance, if the issue is the coolant, you’ll have to spend between $20 and $100.

 Other components that are not so pricey (below $430) include the following: 

The costs we have provided for these components are the maximum rates for each. We also have other components that will cost you a lot to repair, such as: 

  • Radiator~ Between $150 and $1,200
  • Cylinder Head Gasket~ Between $715 and $2,000
  • Water pump~Between $720 and $1,820

Summary

A properly working temperature gauge will save you from immense trouble. 

It means your car will always be cooling efficiently, and thus you won’t experience heat-related engine issues. 

You can avoid such issues by following the elaborate tips provided in this guide. 

Above everything, ensure the radiator’s water levels are within the right range.  

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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