Rheem Water Heater Red Light Flashing [Gas & Electric]

Having worked on many Rheem heaters over the years, I can tell you that the most prominent Rheem water heater red light flashing codes are:

• 2 Flashes
• 4 Flashes
• 5 Flashes
• 7 Flashes
• 8 Flashes

Apart from them, the status light in the heater can also flash nine or ten times. Each of these codes has a different meaning. I’ll discuss all these error codes and their fixes in this guide. So, let’s dive in!

Rheem Water Heater Red Light Flashing [Gas Heaters – How To Fix]

When the Rheem water heater status light blinks red, it indicates something is wrong with it. The exact issue depends on the number of blinks the status light makes. I’ll look at all the red blinking light codes in this section along with their fixes.

i) 2 Red Flashes

The 2 red flashes error code from the status light indicates that the thermopile voltage is low. When the thermopile voltage is low, it won’t be able to power the gas control valve. So, this error code pops up to alert users of the issue.

The main reasons that this 2 flashes code pops up are:

• The thermopile connection is loose.
• The thermopile is faulty.
• Pilot light issues like a dirty electrode or a damaged pilot tube.

How To Fix:

First, you’ll have to inspect the thermopile connection at the gas control valve. If it’s loose, you’ll have to tighten it. If that doesn’t work, you most likely have a bad thermopile and you’ll have to replace it.

You should test it with a multimeter and see if it’s bad before you replace it. If you have issues with the pilot light, you’ll have to replace the pilot assembly. I have a detailed guide on the Rheem 2 flashes error code. Feel free to visit it to learn more about clearing this error code.

ii) 4 Red Flashes

Rheem gas water heaters are notorious for displaying this 4 flashes error code. This status light blinking pattern indicates that the high-temperature limit switch has been tripped.

It’s a safety device that has been designed to protect users from scalding. Usually, this switch trips when the water temperature goes beyond 180 degrees Fahrenheit. The gas control valve shuts off the gas supply and also displays the error code when it happens.

How To Fix:

Unfortunately, the switch is often tripped without a valid cause. That’s why you should try to reset the error code first. I have a guide on the 4 flashes error code. You can scroll down to the section on overriding the error code to get to the good stuff.

If this trick doesn’t work in resetting the code, you should consult a qualified technician. You may have to replace the gas control valve in those situations. But hopefully, the trick will work and you’ll get a steady hot water supply for a long period without any problems.

iii) 5 Red Flashes

If the Rheem water heater LED indicator light blinks red five times, it means temperature sensor issues. Over time, sediments can pile up on the temperature sensor and keep it from working correctly. The temperature sensor can also be defective.

How To Fix:

If the temperature sensor is dirty, you can clean it to erase this error code. Fine-grit sandpaper should do the trick. But you’ll have to replace the sensor if it’s faulty. It’s also a good idea to replace even if it’s just dirty if you prefer a long-term solution.

You have two ways of going about it – you can do it yourself or hire an expert. If you have DIY experience working on your heater, you can take on this project. Otherwise, you should hire a technician.

iv) 7 Red Flashes

Your water heater runs on gas. And that gas supply is controlled by the gas control valve. If there are any issues with this gas control valve, the gas supply can be interrupted. So, you won’t get any hot water.

The Rheem gas water heater blinking 7 times indicates that the gas control thermostat is faulty. It’s bad news for you as this is one of the most important components in a gas water heater.

How To Fix:

If you have a bad gas control valve, the only solution is to replace it. But you can save a lot if you do the replacement yourself rather than hiring a technician. But how do you replace it on your own?

I got you covered. Check out my Rheem gas control valve guide to learn how you can replace it on your own. Moreover, you can also learn about testing and resetting the gas valve in that guide. Hopefully, you’ll find it useful and get the error code to disappear.

v) 8 Red Flashes

The Rheem gas heater blinks red 8 times because of a faulty pilot signal. It could mean two things. The first one is that the thermopile isn’t sensing the flame when the pilot is on. Secondly, the pilot isn’t lit but the thermopile is sensing the flame.

The potential culprits here are a faulty pilot assembly or a bad thermopile. But it can also occur due to gas control thermostat issues. For example, a faulty gas control valve can keep supplying gas to the pilot when it’s in the “Off” position. That can cause the error code to come up.

How To Fix:

You’ll have to find the underlying reason behind the issue and fix it. You’d have to replace the pilot assembly or thermopile if it’s faulty. The same goes for the gas control valve. Once you replace the defective component, the error code should go away.

vi) 9 Red Flashes

There are many Rheem gas heater manuals that stop after showing the 8 flashes error code. So, it’s normal that you’d get confused if you see 9 red flashes as there’s no solution in the manual.

Luckily, this guide will come to your rescue. If your Rheem gas heater has flashed red nine times, it means chamber sensor failure. So, the chamber sensor is either dirty or faulty causing this issue.

How To Fix:

Depending on what’s causing the issue, you’d have to either clean the chamber sensor or entirely replace it. You should test the chamber sensor first to make sure it’s actually faulty before you take further action.

That’s because replacing the chamber sensor takes a lot of work. You’d have to remove the main burner assembly to access it. So, you can save yourself that hassle if it’s not bad by testing it with a multimeter.

Check out my Rheem chamber sensor failure guide to learn about this issue in more detail. You’ll know how to test, clean, and replace the chamber sensor in that guide. Follow the solutions mentioned in the guide to erase the error code from your heater.

vii) 10 Red Flashes

The Rheem water heater blinking red ten times means chamber temperature shutdown. So, the temperature inside the combustion chamber is so high that the water heater shuts off.

The primary reason it happens is when the burner screen is dirty. It occurs due to clogged air inlet openings. Air can’t freely pass from the main burner to the main burner in this scenario. So, the temperature inside the combustion chamber increases and the heater flashes the error code.

This code could also come when there’s a faulty gas control valve. In fact, the gas control valve can cause an error code when it’s faulty. So, you need to be on the lookout for that as well.

How To Fix:

First, you should clean the burner screen. The good news is that you don’t have to take anything apart to do it. You can just locate the air inlet openings in your heater and start cleaning them.

Clean under the heater as well to make sure you free all the air openings. Use the tool of your choice. Vacuum cleaners and wire brushes work great for this job. Make sure there are no obstructions around the air inlet openings. That area should be free.

If that doesn’t solve the issue, it’s likely due to a bad gas control valve. So, you’d have to replace it in that case. Hopefully, that’ll get the code to disappear and you’ll get hot water without any issues.

Rheem Water Heater Red Light Flashing [Electric Heaters – How To Fix]

Rheem electric water heater that has an electronic control also shows an error code to indicate issues with the water heater. Just like the gas heaters, they blink in red color. Here are the codes that you’ll see in these heaters along with their appropriate fixes:

i) 1 Red Blink

There are two thermistors in your Rheem electric water heater. These are important devices in regulating water temperature. When there are issues with any of them, the heater won’t work properly.

If you see the electric heater blinking once, it means the lower thermistor isn’t working correctly. There are two possibilities here. Either the lower thermistor was disconnected or it has completely failed.

How To Fix:

Connecting the thermistor will do the trick if it is just disconnected. However, it’ll need to be replaced if it’s faulty. As the thermistor is an internal component, it’s a good idea to consult a technician to replace it.

ii) 2 Red Blinks

If your Rheem electric heater blinks twice, the common problems behind it are:

• Water contacts the wick or rope sensor.
• Shutoff valve issues.

How To Fix:

If you notice water leaks in the pan of the water heater, you’ll have to seal the source of the leak. The worst thing that can happen here is the leak coming from the tank. You should consult a technician in that case.

You can override the automatic leak detection feature of the water heater for 24 hours if you’re having trouble finding the leak source.  The shutoff valve can be stuck in a closed position and cause this issue. You’d have to reopen it by turning it counterclockwise.

You can visit my Rheem 2 flashes article to learn how you can implement these solutions in detail. Once you take care of the underlying issue causing the error code, it should disappear.

iii) 3 Red Blinks

Some error codes take a lot of work to erase. But one of the easiest codes you can deal with is the Rheem heater blinking thrice. It indicates that the tank is not completely filled with water.

How To Fix:

It’s not hard to put 2 and 2 together if you’re facing this issue. The solution is right there – you have to fill the tank with water. Turn off the power to your heater by turning the breakers.

Then, turn on the cold water supply. Maybe someone had turned it off and that caused this issue. If it’s turned on, maybe there was a lot of hot water demand and it couldn’t keep up. Make sure water is going to the tank of the water heater and wait for it to be filled.

Once the tank is completely filled, you can turn on the water heater. I advise you to wait for a while before using the heater for hot water again. You should be careful not to use the heater when the tank is not filled. It can easily short the heating element and you’ll have to replace it.

iv) 4 Red Blinks

Your Rheem electric heater will blink four times due to the following issues:

• The ECO was tripped.
• One of the heating element’s wires has come loose.
• The heating element wires were switched.
• One or both of the heating elements have failed.

How To Fix:

The ECO gets tripped when the water temperature inside the tank gets too hot. It’s a safety mechanism designed to protect you from scalding. You’ll have to reset the water heater when the ECO was tripped.

The next thing you should check is the wiring issues. If any of the wiring connections are loose, they’ll have to be tightened. If the heating element wires were reversed, you need to arrange them in the correct order.

You’d also have to replace the heating elements if they’ve failed. It’s an easy process if you have experience working with heaters and an element wrench. You’d have to drain the water from the heater first and then proceed to replace the heating element.

I’ve shared how you can implement each of these solutions in detail in my Rheem 4 flashes article. Visit it to learn all about them if you see this code pop up in your heater.

v) 5 Red Blinks

Here are the main reasons why the Rheem electric heater blinks five times:

• The upper thermistor has been disconnected or completely failed.
• Conversion error of the upper or lower temperature.
• The upper or lower element relay is stuck in the on position.
• Something is wrong with the conversion drift.
• There’s an issue with the onboard temperature protection.
• Conversions stuck error.

How To Fix:

The right fix varies depending on what’s causing the issue. I recommend calling Rheem customer support and having them send someone to diagnose and fix the issue.

FAQs:

Conclusion

The Rheem water heater red light flashing is an annoying issue as you’d have no hot water. But now you know how to fix both gas and electric heaters. Hopefully, it’ll be an easy fix and you’ll get the red blinking to stop.

Heaters with other types of gas valves can flash blue even when there’s an error code. Check out my Rheem water heater blue error codes guide to learn more about these codes and their fixes.