Rinnai Tankless Water Heater Troubleshooting! [36 Updated Error Codes Explained] ?

Having problems in your water heater can be very disturbing and especially when there are so many guests in your home to come. If all the hot water faucets are connected to the same water heater, it becomes more difficult for any person to manage the day.

But if you are using the Rinnai Tankless Water Heater, there is a way of a solution to your problems. Thankfully, most of the Rinnai Tankless Water Heaters come with a control display panel and it exactly shows you what the problem with your Tankless Water Heater is.

It shows an error code which allows you to detect the problem and get the instant solution. Well, if you are facing such issues, this guide on Rinnai Tankless Water Heater Troubleshooting will surely help you.

There are almost 35 Error Codes that your Rinnai Heater can display and according to the code, the troubleshooting depends. So you can follow this guide to know more. 

Error Code 02

What is it?

This means that the water heater has been enabled in the freeze protection mode. Thus, the water heater will not work in such a situation.

Troubleshooting

You cannot manually do anything and for better assistance, you need to call a professional.

Error Code 03

What is it?

It means that you went through a power interruption during the bath fill.

Troubleshooting

In such a case, you can follow these few steps mentioned below:

1. First, shut off all the faucets connected with the water heater available in your house. Make sure that the water is not flowing out. 
2. Now you need to get to the temperature controller and press the on/off button twice or more times. This will allow the control unit to be fully reset. 
3. If it does not go and the error code shows up again, there is a problem with the PC board.

Error Code 05

What is it?

Error Code 05 means that you have a problem with your bypass valve.

Troubleshooting

This error is specifically shown to the water heaters which have bypass valves. You can follow the steps below to find the solution. 

1. Turn off the power and close all the hot water faucets connected with the heater. Make sure that no water is coming out. 
2. Next, you need to urn the power on and allow some time to fire up the tankless heater. Once it is done, the error code will be removed. 
3. If the code comes back up again, you may have a problem with the bypass valve. Simply replace it with a new one.

Error Code 07

What is it?

Code 07 means that you may have a problem with the circulation flow rate. 

Troubleshooting

This naturally happens when the circulation flow rate drops below 2.1 GPM. You can follow these steps to know more. 

1. Turn off the power completely and close all the faucets in your home. 
2. Manually check for any type of loose or broken connections in the pump.
3. Check for the power input in the water heater. It must have a minimum of 30 PSI coming in. 
4. Simply drain the tank and confirm that the inlet water is not clogged. Once you check it, try with flushing the drain for once. This will increase the flow rate.

Error Code 10

What is it?

Error Code 10 means that you have problems with your air supply or the exhaust blockage. 

Troubleshooting

Air supply problems can lead to severe damages to the tankless heater. So you can follow the steps below:

1. Start with the vent systems and check for the blockages and clearance issues. You can also check for other issues that can prevent ventilation. 
2. Check the outside vent so that there is no leakage or blockage found. 
3. If you are unable to find the issue, you need to call a professional. However, you can also run some more diagnostic tests for the issue.

Error Code 11

What is it?

Error Code 11 is one of the most common types of errors shown in any Rinnai Tankless Water Heater because of no ignition.

Troubleshooting

In such a case it is always special to contact a professional to know about the error. However, you can follow the few steps mentioned below.

1. Check the valve and the gas meter of the heater. Turn off all the faucets and keep the power on to check the deflection. 
2. You need to check the igniters and know if it is working properly or not. 
3. If it is working properly and still you are not receiving any warm water, you need to contact a professional.

Error Code 12

What is it?

It means two things – either a flame failure or an electrical failure. So it is very important to diagnose the problem before you go to a solution. 

Troubleshooting

1. Check for any visible flame through the window box of the heater. If you see any flame in the burner box, you can assume it is for flame failure. However, if you do not see any flame, it must be of electrical failure. 
2. If there is an electrical fault, there may be a short circuit within the PC. In this case, you need to power off the heater and unscrew the circuit. 
3. Next up, check for the patches and cross-connection. If you are not finding it well to do, you can call a professional.

Error Code 13

What is it?

Error code 13 means that you may have a problem in the combustion. 

Troubleshooting

1. You need to check for the B-vent materials and know if they are properly installed. Check for the rest of the vent systems about their installation.
2. Check for the dip switches according to the altitude.
3. Diagnose from the inlet gas supply and the fire pressures. Once done, just turn on the water heater again and the error code will be gone. 

Error Code 14

What is it?

This is one of the most common types of errors in a heater. It means that you have a problem with the thermal fuse or overheat. 

Troubleshooting

1. Check for the bi-metal switches mounted to the top of the heat exchanged. Allow the unit to cool which will allow the switch to reset. 
2. Next up, you need to check for the Thermo fuses. They are generally present around the heat exchanged. If it is not working, you may have to replace the switches with the new ones. 
3. For this, you need to remove the heat exchanger and then change the thermal fuses. You can call a professional for help.

Error Code 16

What is it?

Code 16 is directly a warning displayed on the screen. It means over temperature warning and the heater has automatically shut down to protect itself from damage.

Troubleshooting

1. You need to start with the air filter and know if it is clean. Look for any type of blockage or clogging in the filter. 
2. Check for the required clearances within the heater and look for their positions. 
3. Know if the vent has any obstructions or not. If there are any obstructions, make sure to clear them.

Error Code 19

What is it?

Code 19 means that there is an electrical short in the wiring present. It is mainly because of a failure in electrical grounding. 

Troubleshooting

If you are not an electrical expert, it is always better to call a professional for troubleshooting. But it is very important to follow the precautions and stay safe. Until the professional arrives, make sure that the heater is turned off. Close all the hot water faucets in the home connected with the water heater.

Error Code 25

What is it?

There may be several issues for the error code 25 and the most common cause is the condensation trap. When it is full, this error may show up. 

Troubleshooting

1. Turn off the power completely and close all the hot water faucets present in the home. Now check for any type of blocks in the drain line. 
2. You may have to open the cabinet and check for the condensate tank. If it is blocked, try to clear the blockage and check again.
3. Now you need to check for the air gap present in the drain line. Now check for the sensor wiring harness. This will help you to check the connections between the PC board and the sensors. 
4. If you are still seeing the error code 25, you need to replace the sensor.

Error Code 30

What is it?

The error code 30 may be a serious issue because your water heater may be showing signs of flammable vapors.

Troubleshooting

1. Check for all the flammable sensors in the water heater and then check for any type of damages present.
2. You need to check for the wiring connections and look for any damages, loose connections or broken connections available. If you find such, repair it immediately. 
3. Allow the heater to cool down and then turn on the power. Open up a hot water faucet to fire the unit. 
4. If the code shows up again. You need to replace the vapor sensor.

Error Code 31

What is it?

It means that you must have a problem with the burner sensor. You can contact a professional who will help you with the problem. 

Troubleshooting

1. Check for the dip switches and look for the fire manifold pressures available. 
2. You need to check for the thermocouple and the mini-volt range present. Check if they are running fine. Now turn on the power and check for the error code. 
3. If the error code still shows up, you need to replace the thermocouple. 

Error Code 32

What is it?

Code 32 is a different issue of the outgoing water temperature. This may happen if your sensor is faulty or having any other issues!

Troubleshooting

1. Immediately turn off the power connection to avoid any type of damages to the body.
2. Open up the water heater and check for the outgoing water temperature. 
3. If you do not know about the sensors, it is wise to call a professional and get the sensors replaced.

Error Code 33

This means that you may have some problems with the heat exchanger. It is responsible for the inlet water supply and converting to the outgoing thermistor. 

Troubleshooting

1. In such a case, you need to turn off the power and check for the connections present inside the thermistor.
2. Check the readings from the resistance to make sure the specifications are good. 
3. Now you need to check or the scale builds up. If there are any rusts, remove and clear them.
4. If it is still not working, replace the thermistor for better results.

Error Code 34

What is it?

The error code 34 means that there is a problem with the combustion in air temperature. This will mostly be displayed on the tankless water heaters.

Troubleshooting

1. Check for the loose connections or damaged connections available in the thermistor. 
2. If you do not find anything, check for the resistance readings along with the specifications.
3. Check for the readings with a Voltameter and get the readings. If there are no readings available, you may have to replace the thermistor.

Error Code 35

What is it?

When your tank shows the error code 35, this means that you have a problem in the temperature sensor. This may be because the sensor is broken and you need to replace it. 

Troubleshooting

1. You need to power off the unit and close all the faucets so that there is no air pressure. 
2. Check for all the connections and the readings in the sensor and the circuit connections. It may be because the sensor is not receiving power. 
3. Turn on the geyser once done. If the error code still pops up, you need to replace it.

Error Code 38

What is it?

If you are seeing the Error Code 38 on the screen, it means that you are having problems with the CO sensor abnormality.

Troubleshooting

1. For this, you need to check for the 4-inch B-Vent materials which will be properly installed. Check for the proper installation of the venting systems.
2. Check for the fire pressures and measure the high and low pressures simultaneously.
3. Next up, check for the dip switches which are available in the circuit. You need to change the CO sensor and the PC board accordingly.

Error Code 41

What is it?

This means that you are having a problem with the Freeze protection sensors. Mostly, this display code is shown on the outdoor models. So it is very important to find out the root cause. 

Troubleshooting

1. The main problem may come from the wiring harness. Check for the circuit and look for any broken or damaged wirings. 
2. The next thing that you need to do is to check for the sensor is covered or not with the insulation. 
3. If you are not being able to do it alone, it will be better to contact a professional.

Error Code 51

Code 51 means that there is a problem with the inlet water temperature. There may be two reasons for this. Either the sensor is having a problem or there is a problem with the internal circuit. 

Troubleshooting

1. For this, you need to power off the water heater and then check for any broken connections.
2. If you find any broken connections, try to repair it and then turn on the power again. 
3. If you still see the error codes, you need to change the sensor. In such a case, it is better to call a professional.

Error Code 52

What is it?

This specific type of error code is common for areas where the air pressure is high. Mainly this problem is because of the modulating solenoid valve. There may be an abnormality in the POV valve. 

Troubleshooting

1. Check for the POV valve and the resistance readings. If you find any problems with it, try to repair it. 
2. Check the input voltage to the valve while it is trying to fire. If you still get the error code, it is time for you to change the PC board or the valve. 
3. It is very important to consult with a professional before you put a step forward.

Error Code 57

What is it?

The error code 57 means that you have a problem with the bi-metal switch fault. In such a problem, the tankless heaters may completely stop working. 

Troubleshooting

1. Check for the POV valves and then also the power input to the POV valves present in the heater.
2. Check the voltage just when the POV is attempting to fire. If you see no deflection, there is a problem with the POV valve. 
3. Since it has many connections, we advise you to call a professional for replacing the valve.

Error Code 58

What is it?

This means that the error code is available because of the secondary heat exchanger sensor. This is basically because of the two b-metals present in the heater and they are open. If you resolve the problem the code will be gone. 

Troubleshooting

1. The problem maybe because of the wiring and thus you need to check the circuit for complete configuration. 
2. If the PCB is fine, you need to check the secondary heat exchanger. Flush it off sure to the scale build-up and then install it again.
3. Turn on the power and the error code will be gone. If it still shows up, you need to clear the drain valve as well. 
4. You need to keep maintaining the sensor if you live in an area with hard water. 

Error Code 61

What is it?

If this error code shows up, this means that you may have a problem with the combustion fan motor. Mostly you may need to hire a professional to check the fan motor. However, you can diagnose the problem alone as well. 

Troubleshooting

1. For this, start with shutting the power and keep the faucets closed so that there is no air pressure. 
2. The problem can also be electrical so try to check the PCB for any type of broken wirings or loose connections. 
3. Check for the fan motor and remove it. Try running the fan motor with separate power! If it moves, you may have a problem with the housing. 
4. In such a case, you need to completely change the fan housing and the fan wheel if there are no obstructions.

Error Code 63

What is it?

This means that the circulation flow rate has dropped to a critical condition. Usually, these error codes show up when the rate is below 1.3 GPM. In such a case, you can follow a few steps for troubleshooting. 

Troubleshooting

1. Check if your water heater is receiving proper power input from the PCB and then operating. 
2. You need to check the heater with a temperature controller and then press the Up button for 3 seconds. This will display your flow rate. 
3. If the flow rate is below 1.3, there may be low air pressure or air obstruction from the pump. You need to vacuum the pump from the system tank and run the heater accordingly.

Error Code 65

What is it?

This means that you may have problems with the water flow servo. If such codes appear, you need to perform a hard reset. If it does not work, you need to call a professional. 

Troubleshooting

1. Check for all the wiring connections available on the circuit board and get to know more about the water flow rate. 
2. You need to turn off the power to the unit and wait for a few seconds to turn it on. 
3. The code should disappear by now. However, if it does not, you may need to place a service call.

Error Code 70

What is it?

Error Code 70 means that it is a problem with the PCB. Your water heater may receive the power, but it may not function properly. There may be several diagnosis checks that you can run before replacing the PCB board.

Troubleshooting

1. Turn off the power completely and then take out the PCB board from the internal tank. 
2. Check for the electrical connections and the lines which will help you to find the fault. 
3. If you do not find any faults, check for the dip switches and the individual power sources. 
4. If nothing works well, you need to replace the PCB immediately.

Error Code 71

What is it?

The error code 71 means that you have a problem in the solenoid valve circuit. There are 4 different solenoid valves and the problem can be in any one of them. There are SV0, SV1, SV2, and SV3. 

Troubleshooting

1. Turn off the power in the water heater and then check for the moisture in the plastic tubing available. 
2. If the moisture is more, you need to vacuum it and run the system again.
3. You need to replace the gas valve and then change the PCB connections. If it is still showing the errors, you need to contact the professionals.

Error Code 72

What is it?

This error code means that you may have problems with the flame sensing device. It may happen at times when the internal temperature is high and flammable. 

Troubleshooting

1. Try to start with inspecting the wiring harness from the flame rods. Look for any type of broken or loose connections available. 
2. Check for the flame rod when unit fires. If you find any type of flames, turn it off immediately.
3. Now you need to remove the flame rod and the look for the carbon content in the tank. Try to clean the carbon contents. 
4. Check the burner and look for any type of rust of sediment formation available. Once you do this, the error code will be removed.

Error Code 73

What is it?

This error code means that you may have an immediate problem in the burner. In such a situation, it is always beneficial for you to consult with a professional. 

Troubleshooting

1. Check for any type of loose connections or damaged circuit conditions available. 
2. If there is no problem with the circuit, check for the dip switches present in the circuit. Pull them out and reset them. 
3. Once it is done, you need to replace the burner thermocouple. This will allow you to remove the error code shown up.

Error Code 79

What is it?

The error code 79 is a serious threat to any water heater and needs some serious repairs. It stands for water leakage from the heater. You can follow the steps mentioned below. 

Troubleshooting

1. Turn off the power immediately and close all the hot water faucets in your home. 
2. Check for the heat exchanger and all the internal piping. If you find drops at the base of the heater, there may be an internal issue. 
3. Pull down the heater and look for the inside cabinet where you may find it to be completely wet. 
4. Replace the particular internal pipe and dry off the leak sensor. Flush out the entire water present and the restart the geyser again. The error code will be gone.

Error Code FE

What is it?

The Error Code FE means that your heater sensor is detecting some flammable vapors present inside the system. It may be due to overheating or some electrical shorts. 

Troubleshooting

1. Turn off the power and then check for the electrical harness present inside the geyser. 
2. Allow some time for the heater to cool down and gently dry it off. 
3. Once it is dry you need to turn on the power to ignite the fire. 
4. If the code reappears, you need to replace the vapor sensor and check the configuration of the PCB.

Error Code FF

What is it?

The error code is a reality check for your water heater. It means that the heater has undergone service just before switching on. 

Troubleshooting:

1. If such code shows, you need to simultaneously press the up and down and on/off switches on the heater.
2. Allow some time for the heater to reset itself and the error code will be gone.

Error Code LC0 to LC9

What is it?

The LC refers to the amount of limescale present in your geyser. So the higher ratings you have the worse situation it is for your heater. 

Troubleshooting:

1. Start by flushing the entire water present in the heater by turning on the hot water faucets. 
2. Allow the heater to reset and it will remove the code. If the code still stays, you may need to call a professional to check the filter and remove the limescale.

Finding error codes in your Rinnai tankless water heater can be a common issue. But with the help of proper diagnosis, you can always avoid serious damages. Well, there are some error codes where you may need the help of a professional.

However, mostly with the help of our guide on Rinnai Tankless Water Heater Troubleshooting things will get sorted for you. Well, we still recommend you to always get proper maintenance done if you wish to have a long life from your water heater.