The 8 1 flashes error code in a Rheem gas water heater indicates that the system is in lockout mode. It usually comes up due to a fault of the flammable vapor sensor. So, how to fix Rheem water heater 8 flashes then 1?
Don’t worry, I’ve solved this issue many times. You’d have to find the underlying cause behind this error code and fix it. The most common reasons behind this code are:
- The FVS is faulty.
- The FVS wiring is corroded or loose.
- Defective gas control thermostat.
More often than not, you’d have to replace the FVS to solve this issue. Don’t worry, I’ll talk about the right fixes for each of the issues mentioned above. So, let’s dive in!
Table of Contents
How To Fix Rheem Water Heater 8 Flashes Then 1 [Explained]
I’ll look at the main reasons behind the 8 1 flash code of Rheem water heaters in this section.
01. Loose Or Damaged FVS Wiring
More often than not, the Rheem 8 1 flashes error code would come up when something is wrong with the FVS. But that doesn’t always mean that the issue will be the sensor itself.
The wiring attached to the sensor can also be defective. Moreover, if the FVS sensor doesn’t have a good connection with its connectors, it won’t work properly. All these issues can lead to the dreaded error code.
How To Fix:
First, make sure that the FVS is tightly connected to its wiring. If it has been loose, you can tighten it and see if that solves the issue. Even if the sensor has a tight connection, the wiring can be corroded or damaged.
So, you have to replace the wiring connectors if they’re damaged. You’ll have to pull out the FVS first to replace the wiring. You should look for the help of a qualified technician here unless you are a trained electrician.
02. Flammable Vapor Sensor Is Out Of Range
The number one reason behind the Rheem 8 1 flashes code is when the FVS goes out of range. When the resistance of the FVS goes out of range, that compromises a safety feature of the water heater.
So, the water heater goes into lockout mode. The good news is that you can easily test if the FVS in your heater is out of range by yourself. If it turns out to be bad, you can take corrective actions to fix the issue.
How To Test Rheem Flammable Vapor Sensor?
The code popping right back up after you reset the FVS is the first sign that it’s bad. That is reason enough to replace it. But the issue can also be the result of a bad gas control thermostat. That’s why you need to test the FVS individually before you go ahead and replace it.
There could also be problems with the wiring and connectivity of the FVS. Make sure it has a tight connection with the wires so that you can get proper results when testing it. You can follow these steps to test the FVS:
- Locate the FVS at the bottom of your heater and disconnect it from its bracket. Then, disconnect the wiring harness and the sensor.
- You’ll need a multimeter to check the resistance of the FVS. Set the multimeter to “Ohms” and attach it to the two terminals of the flammable vapor sensor.
- Note down the reading that comes up in the multimeter.
- If the reading is within the range of 11k ohms to 45k ohms, the FVS is fine. But if it’s outside that range, either way, it’s defective.
How To Fix:
If the test reveals that you have a bad flammable vapor sensor, you’ll have to replace it with a new one. Once you have an FVS that’s within the specified range, the error code should go away.
How To Replace The Rheem Flammable Vapor Sensor?
If the error code pops back up after resetting the FVS and you have tested that it’s indeed faulty, you need to replace it. Here’s how you can do it:
- Shut off the main gas supply to the water heater and unplug the power cord as well.
- Remove the front cover of the main burner and pull the sensor from its bracket with a flathead screwdriver.
- Disconnect the sensor from the wiring. It can be tight at times. So, you may need a pair of pliers to pull it out.
- Then, connect the new sensor and secure it in its place.
- Put the main burner cover back on. Turn on the main gas supply and the electrical power to the heater.
After you reset a faulty FVS, the error code will still remain. You’ll have to reset the gas control thermostat to clear that code. Here’s how to do it:
Unplug the power cord of the heater, wait for two to three minutes, and turn it back on. You have to switch from the highest to the lowest settings a total of seven times. Once you do that, the error code should go away and your gas control valve will be reset.
03. Defective Gas Control Thermostat
If you saw the 8 1 flash error code, you may have replaced the FVS by now. Sometimes, the code may not disappear or come back again soon. So, why does that happen?
It’s often due to a faulty gas control thermostat. The gas control valve is one of the most vital components including in a gas water heater. It controls a lot of things including the FVS to a certain degree.
A faulty gas control valve can lead to a defective FVS in no time. So, your FVS that has gone out of range could be due to the gas control valve.
How To Fix:
If you have a bad gas control valve, you should replace it. But it’s an expensive component. So, you shouldn’t replace it on a whim without making sure that it’s actually faulty and the culprit behind these issues.
You need to follow the right steps to test the gas control thermostat. My Rheem gas control valve guide has detailed instructions on how you can test it. On top of that, you’ll also get to learn about how you can replace the gas control valve if it’s bad.
How To Reset Rheem FVS?
The heater may not always stop showing the error code after you’ve replaced the flammable vapor sensor. Sometimes, you’d have to reset the FVS to erase the error code and get your heater to operate again.
The right FVS reset procedure varies depending on the gas valve you use. You have the Honeywell gas valve if you’re seeing this status light code. So, you can follow these steps to reset the FVS:
- Turn off the power supply and gas supply to your water heater.
- Wait for a few seconds and turn them back on. The next step is important because you have to do it within 30 seconds.
- Move the gas control knob from the lowest to the highest settings. Then, go from the highest to the lowest settings. You have to go back and forth like this 6 times total. You can use a screwdriver to increase the speed of moving the gas control knob.
- The FVS will reset and the error code should be cleared.
However, the reset process will be different if your heater has another type of gas control valve. I’ve covered all the reset procedures for all the common gas valves in my Rheem FVS reset guide. Check it out if you’re interested in learning how the FVS reset system works in other gas control valves.
FAQs:
What does the Rheem 8 2 flashes error code mean?
The Rheem gas water heater flashes eight times, then twice when there’s a fault with the energy cut-off device. You’d have to replace the thermal well of the gas control thermostat to solve this issue in most cases.
What causes 8 4 flashes on a Rheem gas water heater?
The 8 4 flash code in a Rheem gas water heater represents a fault within the gas control valve. You can solve the issue by either resetting the gas control valve or replacing it.
What to do when you see 8 3 flashes on your Rheem gas water heater?
The 8 3 flash code means there’s something wrong either with the thermal well or the gas control thermostat itself. You’d have to replace the faulty component to fix the issue in this case.
What causes 6 3 flashes on a Rheem gas water heater?
There could be many reasons behind the 6 3 flashes error code. The most common ones are gas supply and pilot light issues. Once you fix them, the code should go away.
Conclusion
How to fix Rheem’s water heater 8 flashes then 1? Now that you know the main reasons behind this issue, you should be able to easily fix this error code. It’ll be a bad FVS in most cases. All you have to do is replace it.
If you’re unlucky, the gas control thermostat could be faulty and you’d have to replace it. The fixes aren’t complicated if you follow the instructions. You can check out my guide on Rheem 6 3 flashes if you’re facing that issue.