I’ve worked out the main reasons behind Rheem water heater failed ignition lockout after working on heaters for many years. They are:
- Gas supply issues
- Failed ignition attempts.
- Pilot light issues.
- Main burner problems.
- Faulty gas control thermostat.
- Flue damper issues.
Apart from them, it can also be due to thermocouple issues, a tripped thermal cut-off device, and a faulty FVS sensor. I’ll talk about all these problems along with their solutions in detail in this guide. So, let’s dive in!
Table of Contents
Which Gas Valve Error Codes Represent Ignition Lockout?
There are many error codes that can indicate a system lockout. The only difference between these codes is the reason behind the error. If you have a Honeywell gas valve, you need to look at the blinking pattern of the status light. It’ll reveal what’s the issue.
Here are the most common status light codes that represent failed ignition lockout and their meanings:
- Two Flashes – The flue damper switch is stuck closed.
- Three Flashes – The flue damper switch is open.
- Four flashes – The thermal cutoff device was tripped.
- Five flashes – No flame has been sensed from either the pilot or the main burner.
- Seven fashes – Flammable vapors have been detected.
- Eight flashes – Faulty flammable vapor sensor.
Rheem Water Heater Failed Ignition Lockout [10 Easy Fixes]
I’ll look at the main reasons behind the ignition lockout in Rheem water heaters and their fixes in this section.
01. Failed Ignition Attempts
It’s a common issue in the Rheem gas water heaters that have a White Rodgers gas valve. The heaters have a maximum limit of ignition attempts they can make before it goes into ignition lockout. It’s usually 9 attempts in these heaters.
If the heater failed to ignite even after these 9 attempts, it’ll not start. In the Rheem Gas Prestige Maximus model, the error code A001 indicates this issue. The error code in the gas valve will be the AB fault. It’ll look like this:
How To Fix:
The first thing you have to do is to reset the gas control valve. Usually, that’ll do the trick. Follow these steps to do it:
- Shut off the gas supply to the water heater. You can do it by turning the gas shut-off valve perpendicular to the gas lines. Turn off the blower switch for a few minutes.
- Wait for a few minutes. Then, you can open the gas shut-off valve and turn on the blower switch at the top.
- The igniter should come on at that stage and the main burner should be lit.
The error code will disappear if the unit has been reset. If resetting the gas control valve doesn’t do the trick, there are most likely other issues with your water heater. Keep on reading to learn more about them.
02. Gas Supply Issues
It’s obvious that a gas-powered water heater won’t run without gas. So, it shouldn’t come as a surprise if your Rheem water heater goes to the lockout mode when there’s no gas supply.
If you’re using natural gas, make sure you’ve paid your bills. Turn on another appliance that runs on gas and see if that works properly. If it fires up, that means there’s no issue with the natural gas supply.
For propane gas users, make sure the tank isn’t empty. If it has run out of gas, you’ve just found the culprit. Besides, make sure that you’re using the right gas type for your heater.
Using liquid propane on natural gas heaters won’t work. The opposite of that is also true. Check the rating plate of your heater to find out the right gas type if you’re not sure.
You can also find this information in the manual. Or you can call Rheem tech support and tell them your model number. They’ll guide you on the right gas type of your heater.
Most heaters are equipped with a manual gas shut-off valve. If it’s fully parallel to the gas lines, that means it’s turned on. If it’s perpendicular to the gas lines, no gas would be supplied. So, inspect this valve. If it was in the “Off” position, it’s normal that the heater would go into the lockout mode.
Low gas pressure can also this issue. If the gas supply is on but the pressure is low, adequate gas won’t reach the burner. So, the heater won’t ignite and go into the soft lockout mode.
How To Fix:
First, make sure you’re using the right gas type for your heater. Then, check the gas shut-off valve. Remember that it should be in a fully open position for adequate gas supply. It needs to be completely parallel to the gas lines.
If everything looks good there, the last thing you need to check is the gas pressure. You need a device called a manometer to check it. If you don’t have the tool available and you don’t know how to do it, you should contact your local gas supplier.
The right maximum gas pressure in most Rheem water heaters is 14.0 in. w.c or 3.5 kPa. You’ll also find the minimum pressure in the rating plate of your heater. So, make sure that the gas supply is within that specified range.
If it’s not, adjustments have to be made to the gas supply to the heater. Hopefully, that’ll solve the issue. If everything was okay with your gas supply, there could be another culprit behind this issue. You need to keep on diagnosing until you find the root problem.
03. Flue Damper Issues
The flue damper is an important component of the venting system in a Rheem water heater. If you’re facing this issue in a new heater, there could be issues with it. If the flue damper housing got damaged during shipping, the venting system of the heater will be compromised.
On top of that, the flue damper improves the energy efficiency of the heater. You won’t be able to operate the heater if you remove the flue damper connections. The flue damper should also be free of debris. If there’s any dirt on it, the flue damper won’t work properly.
The most common sign of flue damper issues is seeing the status light flash two or three times. If you see that code, something is wrong with the flue damper and you need to fix it.
How To Fix:
The first thing you need to check is the flue damper wiring and connections. If any of them are loose, you need to tighten them. Hopefully, that’ll solve the issue and you’ll get out of the ignition lockout.
If that doesn’t work, check the damper opening and see if it’s clogged. You need to clean it in that case to solve the issue. If that fails too, then you could have a serious issue with the flue damper.
The flue damper switch could be stuck open or closed. The damper motor could have also gone bad. Your only solution is to replace the flue damper assembly in that case. You can do it yourself if you have the experience. If you don’t feel comfortable doing it, you can hire a technician for the job.
As an added precaution, you should check the venting system of the heater at periodic intervals. The internal flue of the water heater should be cleaned. Remove the flue damper, flue baffle, and draft hood to clean the internal flue when it gets dirty.
The flue baffle needs to hang securely by the collar at the top of the flueway. Make sure you maintain that when you put it back on. If you take these preventive measures, you won’t have to worry about venting issues.
04. Tripped Thermal Cut-Off Device
There’s a device called a thermal well in the gas control valve of Rheem gas water heaters. The thermal well is the part of the valve that goes into the tank. Its main job is to measure the water temperature.
When the water is below the desired temperature, the thermal well signals the gas valve to stay open. The gas valve supplies gas to the main burner and continues to heat the water until the desired temperature is reached.
The thermal well signals the gas valve to shut off the gas supply once that happens. So, the water isn’t overheated.
There’s also another safety device called the thermal cut-off. It gets tripped when the water temperature inside the tank gets too hot to protect people from scalding. It also cuts off the gas supply and keeps the heater from igniting. Your heater can go into the failed ignition lockout mode when it happens.
Now, why are these two devices related? Because a faulty thermal well will inevitably cause the thermal cut-off to get tripped.
Normally, the thermal well would signal the gas control valve to cut off the gas supply when the desired temperature is achieved. But if it goes bad, it won’t signal to cut off the gas supply even when the desired temperature is reached. So, the burner will continue to heat the water and the water will be overheated.
How To Fix:
First of all, make sure that the tank is entirely filled with water. An unfilled tank can cause many issues. Secondly, you have to try to reset the gas control thermostat. You already know the process of doing it for the White Rodgers valve. Here’s how you can do it in Honeywell gas valves:
- Cut off the gas supply to the heater by turning on the control knob to the “Off” position. You can also close the manual gas shut-off valve. Disconnect the power line of the heater from the power outlet.
- Wait for a few minutes and restore the power and gas supply to the water heater.
- Next, you have to do the following things within thirty seconds:
- Adjust the gas control knob from the lowest to the highest settings. Then, go from the highest to the lowest settings. Do it for a total of seven times. You can use a flathead screwdriver to turn the gas control knob faster.
- The status light should start flashing normally and the error code should be erased.
If resetting the gas control valve takes care of the problem, it was a one-time issue. But if the thermal switch keeps tripping, that’s an issue. You’ll see the status light blink four times when it happens.
You’ll have to replace the thermal well as it has most likely gone bad. Once you do that, the new one will sense the temperature properly and keep the heater from overheating. So, you should no longer have any ignition issues.
05. Pilot Light Issues
If the pilot is not lit or doesn’t stay lit for any reason, the main burner won’t come on. Due to failed ignition attempts, the heater can be locked out of the ignition. There are many things that can cause problems with the pilot light.
Some of the most common issues with the pilot light are:
- Gas supply issues.
- Carbon deposits on the pilot electrode.
- The pilot tube is restricted or damaged.
- Damaged pilot igniter wire.
- Faulty emergency cut off device.
- Lack of combustible air.
How To Fix:
You already know how to gas supply problems and what to do about carbon deposits on the pilot electrode. If the issue is with the igniter or the pilot tube, you can try cleaning them first.
But if that doesn’t work, the next course of action would be to replace the faulty components. If you can’t find the defective part as an isolated unit, you’d have to replace the entire pilot assembly.
However, pilot light issues can also be caused by components other than the pilot light. For instance, a faulty Emergency cut-off device will make the pilot constantly go out. Even when the air inlet openings are blocked, the pilot won’t get enough air to light up. The filter crate being clogged will also cause it.
I’ve compiled a guide on Rheem pilot light issues to help you solve all these problems. Hopefully, your pilot light will stay lit after you follow the fixes mentioned in that guide.
06. Clogged Electrode
The pilot electrode in the water heater needs to produce a spark for the pilot light to ignite. If it fails to produce a spark, there’s no question of the main burner coming on. So, the heater will fail after multiple attempts and get into lockout mode.
The main reason that the electrode fails to spark is being clogged with carbon buildup in most cases. The soot that’s formed over time starts to take a toll and causes this issue.
You don’t have to do any guesswork to know if this is the issue. You can easily check it on your own. Remove the main burner front cover and look through the viewport. Press the igniter button a few times. If you don’t see any sparks, you can conclude that the electrode isn’t working.
How To Fix:
The first solution you can implement here is cleaning the electrode. You’ll have to remove the main burner and pull it out to access the electrode. Disconnect all the gas valve connections to the main burner and you’ll be able to slide it out without any issues.
Then, you can clean the electrode and get rid of the carbon deposits. You can use sandpaper to remove the soot from the electrode. Once it’s clean, you can put it back in and see if that solves the issue.
But the electrode can also be broken. In that case, you’ll have to replace it. Besides, it’s a good idea to replace the electrode even if it is just dirty. That’s a good long-term solution. Hopefully, you won’t have any ignition issues with your heater after replacing the electrode.
07. Main Burner Issues
If there are any problems with the main burner, it won’t ignite. After a few attempts, the heater will go into the ignition lockout mode. There’s a lot that can go wrong with the main burner.
Here are the most common issues that make it enter the soft lockout mode:
- Gas supply issues
- Broken or corroded burner ground wire.
- The airflow to the main burner is blocked.
- There is dirt in the intake or exhaust lines.
- Presence of air in the gas lines.
- Dirty or faulty main burner assembly.
How To Fix:
The burner won’t ignite without a proper gas supply. So, make sure there are no gas supply issues. You should be using the correct type of gas. The gas shut-off valve should be fully open. The gas pressure should be within the right range.
Secondly, inspect the condition of the burner ground wiring. If you see any signs of damage on it, you have to replace it with a new one. If you don’t feel comfortable doing it yourself, hire an expert technician for the job.
The burner also needs proper airflow to be ignited. If the air inlet openings are blocked or there are issues with the vents, it won’t work. So, make sure none of those vents are blocked and all sources of air supply are free of dirt and debris.
If there’s air in the gas lines, it needs to be purged out. You can also replace the gas lines with new ones if you want. Finally, the main burner assembly itself could be dirty or faulty. Pull out the burner and clean it if it’s dirty. You’d have to replace it in that case.
08. Faulty Gas Control Thermostat
The gas control thermostat is one of the most important components in a gas water heater. It controls the gas supply to the heater and works with many other components so that the heater runs smoothly. If anything goes wrong with it, that can bring a whole world of problems to your water heater.
A faulty gas control thermostat could stop supplying gas to the pilot and the main burner. So, the heater won’t ignite and get into the lockout mode. The gas control valve can also take the wrong signal from the thermal well. That can also lead to the lockout mode.
The number of places where a faulty gas control thermostat can mess up is endless. Many of those issues can lead to the ignition lockout issue.
How To Fix:
You can first try to reset the gas control valve in case the issue has occurred due to a temporary glitch. But if you have a faulty gas control valve, there’s no quick fix. You’ll have to replace it.
Keep in mind that the gas control valve is an expensive component. Replacing it based on a hunch isn’t a good idea. You need to test it to make sure that it’s actually faulty. Once you can conclude that you have a bad gas control valve, you can go ahead to replace it.
I have a dedicated guide on the Rheem gas control valve that you should read. It’ll walk you through everything you need to know about testing and replacing the gas control valve by yourself.
09. Thermocouple Issues
Not all types of heaters have a thermocouple. Some of the heaters also have a thermopile. They function in a similar way. If you have the Honeywell gas valve, you’d have a thermopile and you can ignore this point.
But if you have the older gas valves, you have a thermocouple in your gas water heater. The thermocouple senses the flame from the pilot. It sends a small current to the gas control valve signaling that the pilot is burning. So, the control valve keeps supplying the gas.
But if the thermocouple stops sensing the signal, the valve will stop supplying the gas. The thermocouple is also a safety device. No gas would go to the pilot if it’s turned off. And the thermocouple makes sure that happens.
The problem is that the thermocouple may not always work properly. Some issues with it can make it collect faulty readings. When that happens, the pilot won’t stay lit. So, the heater will go into the failed ignition lockout mode after a few attempts. The most common issues with thermocouples are:
- Being kinked or moving out of position.
- Getting dirty with time.
- Being broken or defective.
How To Fix:
The right fix for the thermocouple issues depends on the root cause behind the issue. Let’s look at the appropriate solutions for each of these problems:
i) Kinked Thermocouple
The thermocouple needs to be in the right position to sense the flame from the pilot. If it becomes bent, it may move out of its position and not sense the flame properly.
There is a chance that this happened if you’ve recently moved your heater or shifted it from one place to another. The thermocouple could have gotten kinked during shipping.
The fix is simple – you have to put it in its original position. You’ll have to remove the main burner assembly and look at the thermocouple. If it’s bent or out of position, you need to set it to the right position. Then, it’ll sense the flame from the pilot correctly and the pilot will stay lit.
ii) Dirty Thermocouple
Carbon deposits and soot can pile up on the thermocouple. So, it can keep the thermocouple from sensing the pilot flame. You’ll have to clean it to solve the issue. Isolate the thermocouple after pulling out the main burner.
Use sandpaper to scrub the dirt from the thermocouple and put everything back together. If there are no longer any issues with the pilot and the main burner ignites, you’ve solved the problem.
iii) Faulty Thermocouple
Cleaning the thermocouple won’t do the trick when it’s broken or has gone bad. You’ll have to replace it in that case. Besides, it’s also a good idea to replace a dirty thermocouple since it has served most of its lifespan.
Again, you’d have to pull the main burner assembly first. Then, you’ll have to separate the thermocouple. Put the new thermocouple in place of the old one and make sure it sits in the right position. Hopefully, replacing the thermocouple will solve the ignition issues in your water heater.
10. Flammable Vapors Detected
The Flammable Vapor Sensor (FVS) is a safety device installed in some Rheem gas water heaters. As the name suggests, its job is to detect flammable vapors near the heater. Whenever it detects such vapors, the heater goes into lockout mode.
Yes, the FVS gets tripped due to flammable vapors. That’s obvious. But it can also get tripped without any reason if it’s defective. The wiring of the FVS can also be loose and that could also trigger it. Besides, the FVS can be triggered by other things like the chemicals in paint fumes and detergents.
How To Fix:
First, inspect the wiring of the FVS and make sure it has a tight connection. Then, you need to reset the sensor. The process of resetting the sensor will vary depending on the gas valve you use. Luckily, you’ll find how to do it for most gas control valves in my Rheem FVS guide.
If the sensor gets tripped again after resetting it, it has most likely gone bad. You’ll have to replace it in that case. The FVS could also be triggered due to a bad gas control valve.
If you have a bad gas control valve, you’ll have to replace it. The FVS guide will walk you through how you can test the sensor. You’ll also learn how to replace it if it turns out to be faulty. Hopefully, replacing it will solve the ignition issues and you’ll get hot water from your heater once again.
FAQs:
Why is my Rheem gas water heater not heating at all?
Many of the issues that could lead to this problem have already been discussed. Apart from that, the heater may not heat the water properly due to plumbing crossover, sediment build-up in the tank, or faulty mixing valves.
What materials can you use to clean the main burner?
You can use a vacuum cleaner to get the dirt out of the main burner. But you can use a mild detergent if there are any stubborn pieces of dirt or debris. Then, scrub the burner until you get all the dirt out.
How many failed attempts does it take for a Rheem heater to go into lockout mode?
It varies depending on the heater and the gas valves that are used in them. Usually, heaters with a White Rodgers valve go into this mode after 9 failed attempts. For comparison, heaters with Honeywell gas valves are locked out after 3 attempts.
Conclusion:
Now, you know the most common reasons behind the Rheem water heater failed ignition lockout and their fixes. You’ll be fortunate if it’s caused by a simple issue and you can take easy corrective actions.
Hopefully, you’ll be able to get your heater to ignite again after completing this guide. Be patient while doing the diagnosis and check each of the problems one by one. Check out my Rheem gas troubleshooting guidelines if you’re facing other issues with your heater.