Rheem Water Heater 4 Flashes [Reasons + Solutions]

Rheem water heater 4 flashes are the error indication of the high temperature shut down on the water heater. The 4 blinking on the heater red light tells you that the heater water is shutting down due to increasing temperature to an unsafe level. 

rheem water heater 4 flashes

A faulty thermostat damaged electrical wiring, and a bad heating element is the leading reasons for this issue. Also, gas control valve malfunctions, clogged pressure relief valve, or defective high limit switch keeps tripping the reset button.

However, you need to check the thermostat and the high-limit switch first. Whatever has faults, you have to replace the whole thermostat. Also, you may need to replace the gas valve and unclog the pressure relief valve to erase the error. Follow the below article to get a complete guide on this heater problem.

Rheem Water Heater 4 Flashes [Reasons + Solutions]

Before getting into the details, let’s know more about the high-temperature shutdown on the water heater. 

What Does High-Temperature Shutdown Mean On A Water Heater

When the water temperature of the heater exceeds 180 degrees Fahrenheit, the high-limit switch gets tripped and turns the heater into high-temperature mode.

The heater shuts off and stops to heat the water in this mode. Every water heater features a reset button or high-limit switch connected to the thermostat.

It functions as a safety switch in the heater system. When the water temperature exceeds the set temperature or the unsafe level, it senses this and turns off the complete heating system in order to prevent the heater from any overheating damages. Rheem water heater’s red light flashes about 4 times when the heater goes to this mode. 

Note: You can also read how to fix the Rheem Water heater flashing red light 2 times.

What Causes Water Heater High-Temperature Shutdown & How To Fix It

There are 7 major reasons underlying the high-temperature shutdown problem. We have included all these reasons in detail with the corresponding well-proven solution methods. Keep an eye on the below sections. 

1. Faulty Heater Thermostat

In the case of a water heater-tripped high-temperature shutdown switch, a faulty thermostat is a leading reason for this. In every Rheem electric water, there equip two thermostats to regulate the flow of energy.

One is an upper, and the other is a lower thermostat. The main function of the thermostat is to regulate the temperature of the water. Also, it works as a safety switch.

faulty rheem water heater thermostat

When the temperature reaches your set temperature, it shuts off the heating element to prevent the heater from overheating. 

Anyway, though the thermostat gets stuck or stops working, the heating element will continue to heat the water. That leads to the water temperature to an unsafe level. Only replacing the thermostat can fix the issue.

How To Replace Faulty Thermostat In Electric Water Heater

  • Before starting, disconnect the power connection to the heater.
  • Now remove the access panel and safety cover to access the thermostat.
  • Then, disconnect the wiring from the thermostat.
  • You will see that the thermostat is safely placed by a special bracket that holds the device against the tank.
  • Loosen the screws of the thermostat. Now, pry out the bracket from one side by twisting that side of the thermostat upwards. Detach the other side in the same way.
  • Also, disconnect the lower thermostat from the bracket carefully.
  • Place the new thermostat by sliding them evenly downwards into the holding brackets. Make sure the thermostats fit firmly behind the tabs and against the tank.
  • Replace the bracket if it has been damaged during thermostat removal. Reattach the wires. Reinstall the plastic cover and fold the insulation back in place. 
  • That’s all. You have successfully replaced the bad thermostat.

2. Damaged Or Loose Electrical Wiring Connections On The Circuit Board

Loose wire connections on the circuit board are another root reason for this issue. A damaged or loose wiring connection creates high resistance that produces a substantial amount of heat.

That trips the high-temperature shut-off switch and lead to 4 flash error. The problem can be solved by disconnecting and rejoining the wires.


  • Here, you will need to reset the circuits.
  • First, disconnect the wire from the igniter.
  • Then, remove the connector that goes down to the two terminal temp sensors.
  • To remove the cover, unscrew the bolts.
  • Now, disconnect the 2 plastic hooks from the cover and pull the cover out.
  • Remove the two-wire connectors from the circuit board.
  • Wait for 10-20 seconds. Reattach the wire connectors to the circuit board.
  • Plug all the attachments back into their proper locations.
  • Finally, ignite the pilot, and the error blinking should be resolved.

3. Bad Heating Element

The faulty heater element is one of the most common reasons for occurring high-temperature shutdowns on the water heater. Almost all electric water heater features two heating element. One is near the top of the tank.

water heater heating elemant

Another one is at the bottom. Both elements are controlled by the thermostat. The elements allow power to flow through the other elements to heat the water.

Sometimes, the elements continue the function even after the thermostat stops working. When this happens, the inside water temperature starts increasing, and at times, the high limit switches trips.

So, in this troubleshooting stage, you need to check the heating elements whether are in good condition or not. You have to test the continuity of the elements. Follow the below instructions:


  • First, turn off the power connection to the water heater.
  • Anyway, remove the metal covers to expose the elements.
  • Now disconnect the wires that are connected to the terminal screws.
  • You will need an alligator clip and tester probe to test the short circuit of the element.
  • First, clip the alligator clip to any of the element screws. Then touch the tester probe to the mounting bracket of the element.
  • If the light of the tester doesn’t come on, be sure it is defective. You have to replace the faulty heating element.

4. Defective High Limit Switch Or Reset Button

Due to a faulty high-limit switch or the reset button, the Rheem water heater will keep tripping. The reset button is part of the upper thermostat.

Sometimes, the button wears out or burns out, which stops the normal function of the thermostat. Also, it continually trips regardless of the temperature of the water in the tank.


  • Check if the reset button of the water heater is working or not. If it is burnt out, you will have to replace the whole upper thermostat. 
  • We have already provided the needed instructions for replacing the thermostat. 

5. Clogged Pressure Relief Valve

In most cases, the vapor accumulates within the hot water system, which leads to the heater overheating issue. To evacuate the vapors from the water heater, the water heater uses a pressure relief valve. 

But if the valves become blocked with specks of dirt and debris, they will stop working. Consequently, the water heater goes to the high-temperature shutdown mode.


Shut off your water heater. Inspect the pressure relief valve. If it gets blocked, clean the valve immediately. If needed, contact a certified plumber to get this problem fixed.

6. Faulty Gas Control Valve

A defective gas valve is one of the root reasons for occurring 4 flashing on the Rheem heater red light.

Here the solenoid in your heater gas valve may get defective, which leads to valve failure. Whatever the fault reasons, the fact is replacing the gas valve to erase the 4 flashes error from your water heater.


  • Before jumping into replacing the gas valve, make sure you have turned off the gas supply and power line of the water heater.
  • Disassemble the fault gas valve. 
  • Replace it with the new unit.
  • Check the fuel line of the gas valve.
  • If needed, replace the fuel line as well.
  • Contact any certified plumber to precisely do the task.  

7. Bad Thermocouple

If still your Rheem water heater’s red light flashes 4 times, a bad thermocouple would be one of the big culprits. Due to a defective thermocouple, the hot water heater system will go into temperature shutdown mode.

The thermocouple is an essential part of the pilot burner assembly that converts the heat from a burning flame into a small electrical current.

It works as a switch to allow gas flow to the heater. Also, it acts as a safety device to shut off the gas supply when it does not sense a flame from the pilot light. Sometimes, the gas valves continue to flow the gas even after the thermocouple stops working.

That leads to the heater overheating and high temperature shut down. There are a few reasons for thermocouple failure. Like accumulation of dirt on it, cracks in the body, physical damage to the connectors, corroded wiring, bare wire, and so on.


  • First, you should clean the thermocouple.
  • Sometimes only cleaning the thermocouple can get it back to operation.
  • If still, the thermocouple doesn’t function even after cleaning, you need to replace it immediately.
  • Replacing the bad thermocouple is fairly easy, or you can contact any professional to replace the defective thermocouple


How much does it cost to install a Rheem water heater?

There are varieties of models of water heaters with different features manufactured by the Rheem brand. But 50-gallon natural gas water heaters are highly popular. If you want to set up this water heater, the overall cost will be between $900 and $1,700.

Which is better? Is it a 40 or 50-gallon water heater?

The comparison mainly lies in durability and lifespan. The 50-gallon water heater is more durable than the 40-gallon. 40 gallons will last only 7-8 years, whereas the 50 gallons will work fine for about 12-15 years.

Wrapping Words

Hopefully, our guide on the Rheem water heater high-temperature shutdown has been informative enough for you. We can expect, now you clear every responsive factor of 4 times error blinking and how to fix the high-temperature shutdown from the Rheem water heater. 

But still, if you have any queries that have been left behind, don’t hesitate to let us know through comments. We will reply to you with the best answer.

About William

William is the founder of Fireplacehubs.com. 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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