Rinnai Tankless Water Heater Error Codes

Your safety is our #1 priority. Contact Happy Plumbing for further troubleshooting. Our technicians can help you diagnose the problem.

Please note: Your water heater model may use different codes or may provide error codes that are not given here. Therefore you’ll want to consult the manual for your specific heater.

ERROR CODEMEANING
Rinnai Error Code 02No Burner Operation During Freeze Protection Mode.
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Call for service.
Rinnai Error Code 03Power Interruption During Bath Fill (Water will not flow when power returns).
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Turn off all hot water taps. Press ON/OFF twice.
Rinnai Error Code 05By-Pass Flow Control.
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Measure resistance values of the bypass flow control.
Replace the Bypass flow control device.
Rinnai Error Code 10Air Supply or Exhaust Blockage
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check that nothing is blocking the flue inlet or exhaust.
Check all vent components for proper connections.
Rinnai Error Code 11No Ignition (Heating Not Turning On)
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check that the gas is turned on at the water heater, gas meter, or cylinder.
If the system is propane, make sure that gas is in the tank.
Ensure the appliance is properly grounded.
Rinnai Error Code 12Flame Failure – No Flame
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check that the gas is turned on at the water heater, gas meter, or cylinder.
Check for obstructions in the flue outlet.
If the system is propane, make sure that gas is in the tank.
Rinnai Error Code 14The Thermal Fuse Has Been Activated
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check for restrictions in air flow around the unit and vent terminal.
Rinnai Error Code 15Venturi Control
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Call for service
Rinnai Error Code 16Over Temperature Warning (Safety Shutdown Because Unit is Too Hot)
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check for restrictions in air flow around the unit and vent terminal.
Confirm fan motor is functioning correctly.
Rinnai Error Code 17Venturi Blockage
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Call for service
Rinnai Error Code 19Electrical Grounding
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Call for service
Rinnai Error Code 21Data Transfer Error
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Call for service
Rinnai Error Code 25Condensate Pump (Accessory) Condense Trap is Full
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Call for service
Rinnai Error Code 31Burner Sensor Error
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Measure the resistance of the sensor.
Replace sensor.
Rinnai Error Code 32Outgoing Water Temperature Sensor Fault
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Call for service
Rinnai Error Code 33Heat Exchanger Outgoing Temperature Sensor Fault
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Call for service
Rinnai Error Code 34Combustion Air Temperature Sensor Fault
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Rinnai Error Code 38Exhaust Thermistor CO Sensor
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check sensor wiring for damage.
Measure the resistance of the sensor.
The clean sensor of scale build-up.
Replace sensor.
Rinnai Error Code 41Outside Temperature Thermistor Freeze Protection Sensor
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Rinnai Error Code 51Inlet Water Temperature Thermistor (Sensor)
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check sensor wiring for damage.
Measure the resistance of the sensor.
Clean the sensor of scale build-up.
Rinnai Error Code 52Inlet Water Temperature Thermistor (Sensor)
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check for blockage of the main servo
Check the operation of the main servo
The main servo may need to be replaced
Rinnai Error Code 54High Exhaust Gas Temperature
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Ensure Heat Exchanger fins are clean and not blocked.
Confirm inlet water temperature is not too high.
Clear the diagnostic code by resetting the main power supply to the water heater.
Rinnai Error Code 57Burner Overheat Bi-Metal Switch
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Rinnai Error Code 58Secondary Heat Exchanger Sensor
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There is scale build-up in the secondary heat exchanger and it needs to be flushed to prevent damage.
Refer to the flushing instructions in the manual.
Hard water must be treated to prevent scale build-up or damage to the heat exchanger.
Rinnai Error Code 61Combustion Fan Motor Failure
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Ensure the fan will turn freely.
Check the wiring harness to the motor for damaged and/or loose connections.
Measure the resistance of the motor winding.
Rinnai Error Code 63Recirculation Low Flow Circulation Flow Rate dropped below 1.3 GPM
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Ensure the bypass plug is removed and the bypass filter is installed. (Crossover Mode)
Ensure both the inlet water filter and bypass filter are clean and free of debris.
Ensure the Parameter setting are correctly set for recirculation mode.
Ensure Pump supply voltage.
Ensure air is removed from the recirculation line.
Rinnai Error Code 65Water Flow Control Fault
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
The water flow control valve has failed to close during the bath fill function. Immediately turn off the water and discontinue the bath fill function. Contact a state-qualified or licensed contractor to service the appliance.
Rinnai Error Code 70PC Board
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check PC board DIP switches for the correct position.
Check the connection harness at the connection on the PC board.
Rinnai Error Code 71Solenoid Valve Circuit Fault
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Replace the PC board.
Rinnai Error Code 72Flame Sensing Device Fault
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Ensure the flame rod is touching the flame when the unit fires.
Check all wiring to the flame rod for damage.
Remove the flame rod and check for carbon build-up; clean with sandpaper.
Check inside the burner chamber for any foreign material blocking flame at the flame rod.
Measure the micro amp output of the sensor circuit with the flame present.
Replace the flame rod.
Rinnai Error Code 73Flame Sensing Device Fault
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Check sensor wiring and PC board for damage.
Replace sensor.
Rinnai Error Code 79Flame Sensing Device Fault
For your safety and the health of your equipment, contact Happy Plumbing for further troubleshooting
Water has been detected at the bottom of the unit. Turn off the water supply.
Check all plumbing internally for leakage.
Rinnai Error Code LC, LC10, LC1, LC2, LC2 00Scale Build-up in Heat Exchanger (when checking maintenance code history, “00” is substituted for “LC”)
NOTE: The LC code is the only error code that will allow the unit to keep running. The display will alternate between the LC code and the temperature setting. The controller will continue to beep. The LC code will reset if power is turned off and then on.
Flush heat exchanger. Refer to the instructions in the manual.
Replace the heat exchanger.
LC0-LC9 indicates that there is scale build-up in the heat exchanger and that the heat exchanger needs to be flushed to prevent damage. Refer to the flushing instructions in the manual. Hard water must be treated to prevent scale build-up or damage to the heat exchanger.
To operate the water heater temporarily until the heat exchanger can be flushed, push the On/Off button on the temperature controller 5 times. Repeated LC codes will eventually lock out the water heater.
For you safety and the health of your equipment, Call or Contact Silva Mechanical for further troubleshooting
Water has been detected at the bottom of the unit. Turn off the water supply.
Check all plumbing internally for leakage.
Rinnai Error Code SS(SS) Service Soon (Flush Heat Exchanger)
SS is a time-based service indicator set during installation.
See section “3.12 Parameter Settings” for additional details on setting and changing the SS indicator.
SS indicates that it is time for service. The heat exchanger should be flushed to prevent damage (refer to section Flushing the Heat Exchanger for more information).
Hard water must be treated to prevent scale build-up or damage to the heat exchanger.
To reset the SS code, push the On/Off button on the temperature controller 5 times in 5 seconds.
Rinnai Error Code FFMaintenance Has Been Performed
Indicates a licensed professional performed maintenance or corrected an issue