Water Heater Temperature Sensor Failure—What to Do?

Water Heater Temperature Sensor Failure—What to Do?

The temperature sensor for water heater serves as a signal switch. It instructs the gas control valve to release or shut off the gas flow based on the temperature of the water in comparison to a pre-set temperature. However, like other mechanical parts, the temperature sensor can fail, leaving you wondering what to do. Here is what we discovered after consulting an expert. If the water heater’s temperature sensor fails, the water may overheat, become cold, or run out of hot water. To troubleshoot the temperature sensor, do the following:

  1. Measure the temperature sensor’s resistance with a multimeter.
  2. Compare the sensor resistance value to the expected value based on the sensor resistance at different temperatures table provided by the manufacturer.
  3. Replace the sensor if the resistance value is outside the recommended range due to a faulty sensor.

If the water heater temperature sensor fails, you now know what to do. Join us as we discuss how to resolve your water heater issue. It also offers advice on water heater maintenance. Let’s get started.

Causes of Temperature Sensor Failure

Several reasons can contribute to the failure of your water heater’s temperature sensor:


Corrosion might damage the temperature sensor over time. This is especially true in hard water areas or when the sacrificial anode rod is not replaced on a regular basis.

Mineral Deposition

Sediment and mineral deposits can build up around the sensor, reducing accuracy and performance.

Also Read: Rheem Water Heater Blinking Red Light – What Does It Mean?


Temperature sensors, like any other component, deteriorate with age. It may become less reliable or stop working entirely.

Manufacturing Flaws

Temperature sensors may have manufacturing flaws that cause early failure in some circumstances.

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Temperature Sensor Failure Symptoms

It is critical to identify temperature sensor failure in order to prevent further problems with your water heater. Keep an eye out for the following signs:

Water Temperature Variability

If the temperature of your water swings dramatically, it could suggest an issue with the temperature sensor.

There Is No Hot Water

A faulty sensor can result in a complete shortage of hot water.

Error Messages

Many modern water heaters include built-in diagnostics that display problem codes. For more information on interpreting these codes, consult the owner’s manual for your water heater.

Strange Noises

Strange noises, such as gurgling or rumbling, could indicate a temperature sensor malfunction.


Water leaks can occur when a temperature sensor fails.

How to Troubleshoot a Water Heater

A properly functioning water heater ensures that your home has an adequate hot water supply. However, the water heater can fail and require intervention to be repaired. Here are some common water heater problems:

  • Water temperature problems: the water may be too hot or cold, or there may be a lack of hot water. Inadequate power, a faulty temperature sensor, damaged heating elements, or the reversal of hot and cold connections can all cause these issues.
  • Leakage is caused by a faulty T&P relief valve, overheating, or insufficient water pressure.
  • Discolored water could be caused by Anode Rod Corrosion.
  • When the water heater is turned on, deposits can make strange noises.

The steps below will show you how to replace a broken temperature sensor. It also covers T & P valve issues, replacing the anode rod, and removing deposits accumulated during water heater section maintenance. Continue reading!

Is your Rinnai tankless water heater beeping? Learn about all error codes of water heaters in our post: Rinnai tankless water heater beeping.

Checking the water heater temperature sensor

The temperature sensor sends a small current signal to the gas control valve. When the water temperature in the tank falls below or exceeds the specified level, the gas is released, or the gas supply to the burner is cut off. If it fails, no signal is sent to trigger or terminate the heat call.

As a result, the temperature of your water is incorrect. If a high tank temperature causes the trouble code error, turn off the gas control knob for a few minutes before restarting the pilot light.

If the problem persists, check if the temperature sensor is operational.

  1. Disassemble the gas valve with the temperature sensor attached to the water heater’s back plate.
  2. Switch the multimeter to ohms mode.
  3. Connect the multimeter to the pin probe. Pin probes are used to test the pins of small plastic connectors without causing damage to them.
  4. Insert a pin probe into the center hole and another into the outer hole to measure resistance.
  5. Check the water temperature.
  6. Compare the expected resistance at different temperatures with the measurements using the manufacturer’s chart.
  7. If the thermometer is reading correctly, replace the gas valve. Replace the temperature sensor if the reading is incorrect.

Do you have a Rheem water heater, and it’s blinking red? Don’t worry! Read Rheem water heater blinking red light to find out.

Upkeep of a water heater

Water heater maintenance improves operational efficiency and extends its useful life. Some training must be completed only once, while others must be completed annually. Implementing these measures regularly will improve efficiency and lower operating costs for water heaters.

Wrap the water heater in insulation.

Insulating an electric water heater can cut standby heat loss by 25% to 45 percent and water heating costs by 7% to 16%. Because you may be exposed to these risks, it is critical to consult local legislation or the manufacturer’s guidelines before insulating your water heater.

  • You may unintentionally violate operating and safety procedures.
  • They can protect access points like control panels, shut-off devices, and temperature and pressure relief valves.
  • It can also clog the airways required for combustion and ventilation, resulting in hazardous operations.

Control panels, pressure relief valves, temperature controls, instruction manuals, and safety precautions should all be marked and cut into insulators. To ensure safety, turn off the power before insulating the water heater. When the exercise is finished, turn off the power again.

Wrap the pipe in insulation.

Insulating hot water pipes reduces heat loss and allows the lines to receive 2 to 4 degrees Fahrenheit water warmer than uninsulated pipes. As a result, the water temperature setting can be reduced because heat loss is eliminated. It also conserves water by eliminating the need to wait for hot water when turning on the faucet or shower head. It is recommended that when using a gas water heater, the insulation be kept at least 15 cm away from the chimney.

If the water pipe is less than 8 inches from the vent, use a glass fiber pipe wrap that is at least 1 inch thick and does not have a casing. Use wire or aluminum foil tape to secure the pipe jacket and the surrounding area.

Empty the water tank and wash the sediment away.

When hard water is heated, a residue forms on the surface. Because the temperature sensor is not sensitive to the necessary temperature changes, debris on the bottom of the water tank reduces the water heater’s efficiency.

Furthermore, because the deposits cover the heat transfer surface, the water heater uses more energy to heat the water and makes noise when used. Before draining the electric water heater, unplug it from the power supply. If you have a gas water heater, set the gas control to the pilot position.

To avoid stirring the sediment instead of rinsing the tank, it is best to drain the tank first before filling it with cold water. Continue adding water after emptying the tank until clean water flows through the drain hose. Closing the tank drain, refilling the tank, resetting the pilot control, or connecting the water heater are all options.

Also check: Rinnai Tankless Water Heater Beeping—What’s Wrong?

Check The Anode Rod

The anode rod prevents rusting of the steel tank. The anode bar usually lasts 3-5 years, depending on the water quality and the amount of water that passes through the water heater. Water softeners and acidic water both promote anode rod corrosion. Tank wear is reduced by a healthy anode rod.

Furthermore, it reduces sediment buildup at the tank’s bottom. The tank liner may be eroded if you hear loud or multiple noises as the water heater heats up. As a result, it’s possible that the anode rod needs to be replaced.

  1. Turn off the gas or electric water heater’s water and fuel supplies.
  2. Connect the garden hose to the tank’s drain and drain about 10% of the tank’s capacity.
  3. Examine the anode rod’s position.
  4. Unscrew the hexagonal head. Loosening the hex head requires much force, so it’s best to have another person hold the water heater in place to protect the pipes and other accessories. By sliding a small piece of the metal tube onto the impact socket, you can generate the force of a lever.
  5. Remove the anode rod after loosening the hexagonal head. Please consult an expert if removing the anode bar is too tricky.
  6. Install a new anode rod and securely fasten it. Plumbing tape should be wrapped around the connecting thread of the new anode rod.

How Do You Fix A Water Heater Temperature Sensor Failure?

Maintaining your water heater regularly will help it last longer and run more efficiently. Furthermore, if you are going to be away from home for at least three days, you should turn off the water heater. It lowers the heating system’s operating costs and saves energy


About Author

Mobeen Shahid

Mobeen Shahid

Mobeen Shahid is a Mechanical Engineer with two years of experience in the HVAC industry. His passion is analyzing HVAC issues, and he works relentlessly to devise customized solutions. He has been in the industry long enough to know the ins and outs and ensures that areas are optimally heated, cooled, and ventilated.

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