Honeywell Water Heater Sensor Failure [Reasons + Solutions]

Within the water heater heating system, the sensor plays a big role in controlling the heating function. All the water heaters are equipped with a temperature sensor which functions as a signal switch to the gas control valve. 

honeywell water heater sensor failure

Like other well-known brands, Honeywell heater owners also face various faults from the temperature sensor. The root reasons behind the Honeywell water heater sensor failure include accumulated sediment in the equipment or a defective sensor due to wrong resistance.

However, in the troubleshooting stage, we will ensure that the sensor needs replacement by measuring the resistance. From the below comprehensive article, we have already explored how to troubleshoot your water heater temperature sensor. So, without any delay, let’s get into it.

Honeywell Water Heater Sensor Failure [3 Easy Solutions]

Before moving to the details guide on Honeywell temperature sensor failure 5 flashes, let’s learn the symptoms of a defective heat sensor from below:

Note: You can also read how to fix Honeywell hot water heater status light blinking problem.

What Are The Signs Of A Temperature Sensor Failure On A Hot Water Heater?

The temperature sensor is an essential element in the water heater. It is used to manipulate the gas valve through a small electric current. The sensor signals the gas valve based on the water temperature and functions whether the valve needs to release or terminate the gas supply.

However, due to several reasons, the sensor gets defects and fails to continue its normal operation. There are a number of ways that tells heater heat sensor failure. 

Pay attention to the following warning signs to understand if you need heater sensor replacement:

  • Honeywell status light blinking 5 times: If you notice the heater status light blinking 5 times, be sure it’s a problem with the water temperature sensor. 5 times blinking is the error indication of sensor failure.
  • Water is not getting hot enough: If you find that your hot water supply fails to reach your desired temperature, the bad temperature sensor is the leading reason here. Due to a faulty sensor, the water will not raise the water temperature.
  • The water is getting too hot: Overheating is a sign of a malfunction of a temperature sensor failure. Because of a bad sensor, the water temperature will rise to an unsafe level which is very dangerous.
  • Gas Control Valve failure: The valve function is highly related to the heat sensor. Thus, a defective sensor will never send signals to the gas valve, which causes various problems in the valve function. Mostly it prevents the heater from warming the water at your desired temperature. 

1. Power Cycle The Heater

If you are noticing several malfunctions from the heater element relating to temperature sensor failure, your first step would be doing a power cycle on the heater. 

pressing the igniter button and pilot knob

It is effective troubleshooting, and there is a higher chance of turning back the heater to normal function. Here are the steps that you have to follow:


  • First of all, turn the gas control knob to the Off position.
  • Pull off the outer door of your water heater.
  • Leave the heater in position for 5-10 minutes.
  • This will assist in moving out all the accumulated gas inside of the heater.
  • After that time, relight the pilot.
  • For this, turn the control knob to the “Pilot” position.
  • This time, you have to push the knob button all the way in.
  • At the same time, press the piezo igniter button. Keep depressing the button simultaneously unit you will hear a loud clock sound. You’ll also find the stay light starts blinking.
  • This indicates that the pilot is now lighting. Now you can set the knob to your desired position. 
  • If the resetting doesn’t work, you need to test the temperature sensor. Go to the below section.

2. Test The Temperature Sensor

In the next step, you have to test the temperature sensor. In many cases, the temperature sensor fails if the resistance is out of range going through it. You can’t assume that the sensor is faulty until you measure its resistance of it. 

So, it is needed to know if the temperature sensor is going out due to incorrect resistance or not. This will define if the sensor is still working or not. Follow the below instruction to test the sensor with a multimeter.

How To Test The Honeywell Water Heater Temperature Sensor

  • For testing, you need to access the temperature sensor. 
  • Disassemble the gas valve and get access to the sensor.
  • But make sure you are leaving the temperature sensor attached to the water heater’s backplate.
  • Now, take a multimeter and set it to ohms.
  • Then, attach the multi-meter to the pins on the plastic connectors. Get pin probes for the connection. This will ensure testing the pins on the small plastic connectors quite safely and without damaging them.
  • After that, insert one pin probe into the center hole.
  • At the same time, connect the other probe to an outside hole.
  • Now, look at the resistance reading. Also, measure the water temperature.
  • Get your heater manufacturer’s chart. Then compare the resistance at different temperatures with the readings.
  • If the resistance reading is all ok, then there is nothing to be worried about the sensor.
  • Here the gas control valve is faulty, and you need to replace the defective gas control valve.
  • On the contrary, if the reading is off, you need to replace the temperature sensor. Follow the below section to get a complete guide about water heater temperature sensor replacement.

3. Replace The Dead Temperature Sensor

There are a few signs of a bad temperature sensor. That includes:

  • The temperature sensor is accumulated with dirt and debris, which can be fixed by just cleaning it.
  • Broken or bent sensor.
  • Loose connection of the sensor 
  • Wrong voltage reading or the worn-out sensor.

Anyway, whatever the symptoms are, you need to replace the faulty temperature sensor. All the process involves the following:

Collect The Required Tools

Here is the list of tools that you need while replacing the temperature sensor:

required tools
  • 11/32 nut driver/socket
  • T20 Torx
  • ¾ inch wrench
  • ½ inch wrench
  • 7/16 inch wrench
  • 3/8 inch wrench

How To Replace Temperature Sensor On Water Heater

Go through each of the steps to replace the bad temperature sensor efficiently:

faulty temperature sensor
  • First of all, shut off the gas shut-off valve
  • Then, you need to disconnect the thermopile.
  • Also, remove the igniter from the gas valve.
  • Now take the 7/16-inch wrench and disconnect the pilot gas supply.
  • In order to disconnect the main gas supply, use ¾ inch wrench.
  • Then, you have to remove the heater’s front door, which is attached with two screws. Take T20 Torx and unscrew the screws.
  • Also, remove the attached nut using a nut driver.
  • Remove the screws of the burner assembly and pull it out.
  • Then, loosen the sensor using the wrench and remove the faulty sensor by unscrewing it.
  • After that, you have to replace the new sensor there. For this, first, place the sensor head in the front place.
  • Connect the hex rod to it.
  • Ensure a tight connection of the sensor is in place.
  • Finally, reassemble the complete heater by reversing the above steps.
  • Great job! You have replaced the faulty temperature sensor from the heater successfully.
  • Still, if you face any problems, contact a certified plumber to do this precisely. 


What does the status light mean on a water heater?

All the water heaters feature a status light which is used to know if the heater is working properly or not. If the status light once will usually indicate ‘normal operation.’ But blinking several numbers of times defines various errors from the heater function.

Is the Blinking Water Heater Light Dangerous?

A blinking on the status light you error messages from the heater function. It is not a sign of danger but just informing you that there is something up with your water heater. 

How do you know if your water heater is going to explode?

The major signs behind the water heater are going to explode is water leaking, defective pressure relief valve, strange noise from the heater element, or sometimes lack of hot water. All the signs are quite dangerous and need immediate troubleshooting. 

Wrapping Thoughts

Well!! We are almost to the end of the article. Expectantly, we can reach out to you in every aspect related to Honeywell hot water heater temperature sensor failure. 

Troubleshooting this sensor will not seem a hard task as long as you will follow the above well-proven guide. But still, if you have any questions or queries on any discussed fact, don’t delay to let us know through comments.

 We will bring the quick and best answer to you.

About William

William is the founder of He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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