Rheem Water Heater Error Codes

If there is ever a problem with your Rheem water heater, you can consult our list of error codes to find out what actions you should take to fix the unit.

The Complete List of Rheem Water Heater Error Codes

Error Code 00

1 hour of continuous combustion.

A water heater is not exactly designed to run for that long. So, shut off the hot water taps and turn off and remove the circulation pump, if you have one.

Read: How Many Amps Does Water Heater Use?

Error Code 05

Imperfect combustion alarm.

The chances are high that the heater will be able to operate with this error, but you should still try to fix the problem.

An issue with the combustion can take place because of a blocked vent exhaust or a problem with the airflow.

Simply inspect the exhaust vent and pipes and get rid of any obstructions and clean the air filters and the fan.

Error Code 10

A false flame has been detected.

Make sure that the vents and the flue inlet are not blocked and that the heat exchanger is nice and clean.

You might have to invite a professional to take care of this one.

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Error Code 11

No ignition.

Here are a few questions that will help you identify the root cause of the problem:

  • Do you have gas connected to the appliance?
  • Are the valves turned on?
  • Does the unit have the right gas pressure? Usually, an expert would be able to determine that with special equipment.
  • Is there an issue with the igniter?
  • Is everything okay with the igniter’s wiring?

Error Code 12

No flame.

Make sure that you have gas connected to the unit and that all the valves are open. Also, inspect the flame rod – the wire should be properly connected and the component should not be dirty.

Error Code 13

Improper (or poor) combustion.

You might see this error code if you have an indoor tankless system.

There is, most likely, a problem with the blower motor, flame rod, or exhaust venting.

Error Code 14

An overheat wrap fault. 

Ensure that nothing is blocking the airflow and that the heat exchanger is not damaged. 

A bad safety circuit or a gas problem might also be to blame, so calling a professional may be the best decision.

Error Code 15

Boiling safety device.

This means that your heat exchanger has maintained 207 F for over 15 seconds.

The unit’s inlet valve has to be fully open and there shouldn’t be any obstructions in the cold-water inlet pipe.

You can also try flushing sediment out of your heater.

Error Code 16

An over-temperature warning.

The temperature of the water is above your thermostat settings.

Make sure that nothing is blocking the airflow and the heat exchanger. Get rid of any limescale buildup.

Error Code 21

A malfunction of the air intake filter switch.

The front panel has to be installed correctly and the air filter cover has to be seated properly. 

Error Code 24

A malfunction of the operational switch. 

Here are a few tricks that you can try out:

  1. Shut the water off and carefully disconnect the remote control. Put everything back in place and see, if the error persists.
  2. Reset your Rheem water heater (press the ‘min’ and ‘max’ buttons on the control board).

If nothing helps, then an expert would have to replace the control board. 

Error Code 29

The heat exchanger’s outlet temperature is too low. 

If you have a condensing unit, then:

  • Clean the air inlet screen and the heat exchanger’s fins.
  • Make sure that there are no blockages in the drain line.
  • Clear the neutralizer drainage ports and the drainage line.

Error Code 31

A water inlet temperature sensor fault.

If you have experience working with wiring, then you can ohm the thermistor, make sure that the wires are properly connected and not damaged, and clean the component if it has lime buildup.

Error Code 33

An outgoing water temperature sensor fault.

Follow the same instructions mentioned above (error code 31). If nothing helps, a professional would have to replace the sensor. 

Error Code 34

A combustion air temperature sensor fault.

Follow the instruction provided for error code 31.

Also, make sure that there are no obstructions affecting the airflow and check the fan blade (you should be able to spin it freely).

Error Code 35

An improper thermistor connection.

A thermistor is the part of the system that makes the gas valve stop sending gas to the burner as soon as the water reaches the right temperature.

When such an error occurs, check the thermistor connections (they have to be secure).

Error Code 51

A gas valve fault.

Make sure that there are no loose or damaged terminals on the valve.

Do bear in mind that you might have to invite a professional over for this one.

Error Code 52

A fault of the modulating solenoid valve.

You can, once again, check for loose or damaged terminals, but better leave this job to a professional. 

Error Code 61

A combustion fan failure.

Try turning the fan’s blades with your hands – they should be able to move freely. Also, make sure that the connections on the motor are not damaged and are properly fitted.

Error Code 65

An issue with the water control valve.

Inspect the water control valve to make sure that there are no damaged connections.

If you think that you are able to do that – check the voltage of the valve (you’ll need a good-quality multimeter for that).

Read: Top Reasons Why Furnace is Leaking Water

Error Code 66

An issue with the water bypass valve.

Just like with the previous error, carefully inspect the wiring and check if the solenoid has the right voltage.

Error Code 71

A gas control valve fault.

Look for damaged or loose connections. If everything seems to be okay, then call an expert.

Error Code 72

An issue with the flame sensing device.

  • Inspect the burner chamber – there shouldn’t be any blockages or foreign materials.
  • Make sure that the flame rod is touching the actual flame when the heater ignites.
  • Clean the flame rod, if necessary. Also, check the component for damage.
  • If you can, check the rod’s voltage.

Read: How Long Do Flame Sensors Last?

Error Code 76

There is a communication fault with the remote control.

Check the remote control’s wiring

If everything seems to be okay, then you can try connecting the control directly to the remote connection (you’ll find it at the bottom of your Rheem water heater). If this made the error go away, then the cable is the problem.

Error Code 79

A fan motor current fault.

Try manually turning the fan – it has to turn freely. If you can, make sure that the component has proper voltage.

At times, the motor can get damaged due to condensation. Carefully inspect the component to find out, if that’s the issue.

Read: Why Furnace Blower Motor Hums But Won’t Start?

Error Code 80 and 81

An issue with the gas control valve.

Call a professional. The expert is going to check the voltage and replace the component, if necessary.

Error Code 82

The control board is not programmed.

  • Is the program chip installed?
  • Is the control board programmed for the right type of gas?

Error Code 90

The flue or air intake is blocked.

Check the heat exchanger, the blower motor, the exhaust flue, and the inlet flue for blockages.

Read: Does A Furnace Room Need Ventilation?

Error Code 92 and 93

The neutralizer has to be replaced. 

A neutralizer is a vessel that is filled with media that raises the pH level of the condensate produced by the water heater.

You will see this error only if you have a condensing model. Simply replace the neutralizer.

Error Code 99

The blower motor is not able to vent.

Check the venting and exhaust flue, the heat exchanger, the combustion fan, and the inlet filter for blockages.

Error Code P1

The water flow is too low.

You might need to:

  1. Clean the aerators.
  2. Clean the water inlet filter.
  3. Adjust the temperature or increase the flow rate.
  4. Check the water flow sensor (if the steps mentioned above did not help).

Error Code 1L

There is limescale buildup in the system.

Your water heater needs to be flushed.

If you decide to do that yourself, make sure to consult the owner’s manual, and don’t forget that water in the unit can be extremely hot.

Tip: don’t use any chemicals to flush the water heater. Ordinary vinegar is a much safer option.

Read: No Hot Water In The House? Here’s Why