Rheem Error Codes

    Rheem Tankless Error Codes or Fault Codes

    Your Rheem water heater has an electronic diagnostic system built directly into it. When your water heater finds a problem, it displays an error code in the LED display on the remote control or the front panel. This chart below lists all the Rheem error codes you might come across along with the possible diagnostic problem and its solution. Using this chart may help you diagnose and/or fix a problem you may be experiencing.

    NOTE: DEPENDING ON ERROR SEVERITY RHEEM PUTS THE TANKLESS INTO EITHER A SOFT LOCKOUT OR A HARD LOCKOUT. A HARD LOCKOUT INDICATES A MORE SERIOUS SITUATION SUCH AS FLAME, IGNITION, OR CONDENSATE PROBLEM.

    TO CLEAR A HARD LOCKOUT ERROR CODE PRESS THE POWER BUTTON.

    If you are unable to fix your Rheem error code you should call your tankless installer, a tankless professional, or possibly Rheem directly to address your issue.

    An alternative option for rectifying errors is to reboot your Rheem tankless.
    1. Unplug the water heater from power, wait about 1 to 2 minutes then plug it back in.

    Error Code 1L

    FAULT = 1 Hour continuous combustion

    1. Flush tankless to remove scale and lime buildup.

    Replacement Parts or Equipment

    Error Code 00

    FAULT = 1 Hour continuous combustion

    1. Close all hot water taps to reset unit.
    2. Turn off, or remove circulation pumps (unit is not designed for continuous operation with circulation systems).

    Replacement Parts

    • Not Applicable

    Error Code 05

    FAULT = Imperfect Combustion

    1. Clean air inlet filter.
    2. Clean combustion air fan.
    3. Clean heat exchanger fins.
    4. Check for adequate combustion air ventilation openings and clean if necessary.
    5. Check vent system for partial blockage and correct as necessary.

    Replacement Parts

    Error Code 10

    FAULT = Flame has been lost Eight (8) Times

    Press the Power button to clear the Error Code.
    If Error happens again:

    1. Monitor the gas pressure to the water heater while in operation and ensure pressure is between 5.0″ W.C and 13.0″ W.C (1.25 to 3.24kPa).
    2. Check gas valve wire. Ensure connection is secure.
    3. Check flame detection sensor. Ensure connections are secure. Normal operating settings are more than 2.5DC before ignition, less than 2.5DC after ignition.
    4. Check igniter transformer for proper connection.
    5. Clean the spark igniter with steel wool to remove oxides and ensure proper separation of 3-4 mm.
    6. Replace the spark igniter if damaged.
    7. Assure that the flame is stable when lit.
    8. If the problem persists, replace the main control.

    Replacement Parts

    Error Code 11

    FAULT = 1 Hour No Ignition or Ignition has Failed 10 (Ten)
    Times

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Monitor the gas pressure to the water heater while in operation and ensure pressure is between 5.0″ W.C and 13.0″ W.C (1.25 to 3.24kPa).
    3. Check gas valve wire. Ensure connection is secure.
    4. Check flame detection sensor. Ensure connections are secure. Normal operating settings are more than 2.5DC before ignition, less than 2.5DC after ignition.
    5. Check igniter transformer for proper connection.
    6. Clean the spark igniter with steel wool to remove oxides. Ensure
    7. proper separation of 3-4 mm.
    8. Replace the spark igniter if damaged.
    9. Assure that the flame is stable when lit.
    10. Ensure gas type and pressure is correct.
    11. Bleed all air from gas lines.
    12. Ensure gas line, meter, and regulator are sized properly.
    13. Ensure appliance is properly grounded.
    14. If the problem persists, replace the main control.

    Rheem Replacement Parts or Equipment

    Error Code 12

    FAULT = Flame Failure

    1. Ensure you have gas to the appliance.
    2. Ensure gas type and pressure is correct.
    3. Bleed all air from gas lines.
    4. Ensure flame rod wire is connected.
    5. Check flame rod for carbon build-up.
    6. Ensure gas line, meter, and regulator are sized properly.
    7. Ensure appliance is properly grounded.
    8. Check gas solenoid valves for open or short circuits.
    9. Check power supply for loose connections.
    10. Check power supply for proper voltage and voltage drops.
    11. Disconnect remote control.
    12. Disconnect and re-connect all wiring harnesses on unit and PC board.
    13. Ensure proper venting material was installed.
    14. Ensure condensation collar was installed properly.
    15. Ensure maximum vertical vent length does not exceed allowable limits.
    16. Ensure maximum horizontal vent length does not exceed allowable limits.

    Replacement Parts or Equipment

    Error Code 13

    If this code is displayed

    • Contact a dealer or qualified service technician.

    Replacement Parts or Equipment

    • Not Applicable

    Error Code 14

    FAULT = Overheat Wrap Fault

    1. Flush tankless to re1.Ensure high fire and low fire manifold pressure are correct.
    2. Check gas type of unit and ensure it matches gas type being used.
    3. Check heat exchanger for cracks and/or separations.
    4. Ohm out safety circuit.
    5. Check for improper conversion of product.
    6. Check for restrictions in air flow around unit and vent terminal.
    7. Check for a foreign materials in combustion chamber and/or exhaust piping.

    Replacement Parts or Equipment

    Error Code 15

    FAULT = Boiling Safety Device

    1. Check for closed water heater inlet valve or restrictions in cold water inlet pipe(must be fully open).
    2. Check for clogged heat exchanger (scale buildup).
    3. On commercial water heater, lower set-point temperature below 180F at high altitude.

    Replacement Parts or Equipment

    Error Code 16

    FAULT = Operating Temperature Sensor or DHW Sensor detects Water Temperature Greater than 199°F (93°C)

    1. This Error Code will go away when the DHW temperature decreases. If Error happens again:
    2. Check if dip switch High Fire setting is ON. Switches 6 and 7 should be OFF for normal operation.
    3. Check if DHW pipe is blocked. Ensure there is enough water flowing to the water heater.
    4. Check DHW sensor at DHW outlet. If resistance is zero, replace the sensor.
    5. Check Operating Temperature sensor at the heat exchanger. If resistance is zero, replace the sensor.
    6. Check for clogged heat exchanger.
    7. Check for restrictions in air flow around unit and vent terminal.
    8. Check for a foreign materials in combustion chamber and/or exhaust piping.
    9. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 20

    FAULT = High Limit Overheat Switch – Closed is Normal, Open is Fault

    1. Press the Power button to clear the Error Code.
    2. Inspect the High Limit Overheat switch. Ensure proper connections.
    3. Check High Limit Overheat switch resistance. If resistance is zero, replace the switch.
    4. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 21

    FAULT = Malfunction of Air Intake Filter Switch

    1. Make sure air filter door is properly seated.
    2. Make sure front panel is properly installed.

    Replacement Parts or Equipment

    • Not Applicable

    Error Code 24

    FAULT = Malfunction of Operational Switch

    1. Press max button on PCB to reset.
    2. Press min button on PCB to reset.
    3. Replace PCB

    Replacement Parts or Equipment

    Error Code 29

    FAULT = Heat Exchanger Outlet Temp. Too Low

    1. Clean heat exchanger air inlet

    Replacement Parts or Equipment

    • Not Applicable

    Error Code 29

    FAULT = Neutralizer clogged – Closed is Normal, Open is Fault.

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Check APS/Condensate and main controller connections. Ensure all are secure.
    3. Check APS/Condensate resistance. If resistance is zero, replace the switch.
    4. Check APS/Condensate hose. Ensure it is connected and in good condition.
    5. Check condensate line and termination for blockages.
    6. Replace condensate neutralizer.
    7. Check exhaust vent for blockages.
    8. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 31

    FAULT = Water Inlet Temperature Sensor Fault

    1. This Error Code will go away when inlet water temperature decreases. If Error happens again:
    2. Check inlet water temperature sensor. Ensure connections are secure.
    3. Check sensor wiring for damage.
    4. Check and clean scale from sensor.
    5. Check sensor resistance. If resistance is zero, replace the sensor.
    6. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    • Not Available

    Error Code 32

    FAULT = Water Outlet Sensor Open or Short

    1. This Error Code will go away when inlet water temperature decreases. If Error happens again:
    2. Check inlet water temperature sensor. Ensure connections are secure.
    3. Check sensor wiring for damage.
    4. Check and clean scale from sensor.
    5. Check sensor resistance. If resistance is zero, replace the sensor.
    6. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 33

    FAULT = Outgoing Water Temperature Sensor Fault

    1. This Error Code will go away when inlet water temperature decreases. If Error happens again:
    2. Check inlet water temperature sensor. Ensure connections are secure.
    3. Check sensor wiring for damage.
    4. Check and clean scale from sensor.
    5. Check sensor resistance. If resistance is zero, replace the sensor.
    6. If the problem persists, replace the main control

    Replacement Parts or Equipment

    Error Code 34

    FAULT = Combustion Air Temperature Sensor Fault

    1. Combustion Air Temperature Sensor Fault

    Replacement Parts or Equipment

    • Not Available

    Error Code 35

    FAULT = Exhaust Sensor Open or Short

    1. This Error Code will go away when exhaust temperature decreases. If Error happens again:
    2. Check exhaust temperature sensor. Ensure connections are secure.
    3. Check sensor resistance. If resistance is zero, replace the sensor.
    4. Check exhaust vent for blockage.
    5. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 35

    FAULT = Improper Thermistor Connections

    1. Check that all thermistors are connected to proper connections on PCB.

    Replacement Parts or Equipment

    • Not Available

    Error Code 39

    FAULT = Flame Detected after Exiting a Flame On Condition

    1. This Error Code will go away when the false flame condition is remedied. If Error happens again:
    2. Check the water heater cover. Ensure it is secure. Flame detection sensor can detect an external light source.
    3. Check flame detection sensor. Ensure connections are secure. Normal operating settings are more than 2.5DC before ignition, less than 2.5DC after ignition.
    4. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 40

    FAULT = Gas Leakage continuously detected for 10 Minutes, or three times within One Hour

    IMPORTANT: If you smell gas, STOP! Immediately evacuate and call your gas supplier or a qualified service technician from outside or from a neighbour’s phone.

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Check the water heater cover. Ensure it is secure.
    3. Check gas connections for leakage with a soapy solution. Fix any leaks.
    4. Check condition of the burner assembly.
    5. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    • Not Applicable

    Error Code 41

    FAULT = Fan Speed too High with Flame On

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Check the vent connections for blockages.
    3. Check the burner assembly.
    4. Check fan operation. If fan appears to be operating normally but RPMs are too low or too high, replace the fan.
    5. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 43

    FAULT = Burner Overheat Switch Open

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Check burner overheat switch connections. Ensure connections are secure.
    3. Check switch resistance. If resistance is zero, replace the switch.
    4. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 44

    FAULT = Recirculation Abnormality

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Ensure water heater inlet and outlets are open and water is supplied to the water heater.
    3. Check the pump operation.
    4. If it doesn’t work, ensure wiring connections to pump.
    5. If even supply power to pump and doesn’t run it replace the pump. If Error happens again:
    6. Verify recirculation loop length is within specification. Air purge is not enough.
    7. Too much restriction on recirculation loop.
    8. Return loops are clogged.
    9. Check the recirculation loop condition

    Replacement Parts or Equipment

    Error Code 45

    FAULT = Water Leak

    1. Turn power off to the water heater.
    2. Turn supply water valve off going to the water heater to isolate it from the system.
    3. Call a qualified service technician to diagnose and repair the source of the leak.

    Replacement Parts or Equipment

    • Not Applicable

    Error Code 51

    FAULT = Gas Inlet Solenoid Valve Fault

    1. Check gas inlet solenoid valve wiring harness for loose or damage terminals.
    2. Ohm out solenoid valve.
    3. Replace if necessary

    Replacement Parts or Equipment

    Error Code 52

    FAULT = Modulating Solenoid Valve Fault

    1. Check modulating gas solenoid valve wiring harness for loose or damage terminals.
    2. Ohm out solenoid valve.
    3. Replace if broken or out of specifications

    Replacement Parts or Equipment

    Error Code 60

    FAULT = Hot Water Temperature Abnormality

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Ensure water heater inlet and outlets are open and water is supplied to the water heater.
    3. If Error happens again:
    4. Ensure water heater inlet and outlets are open and water is supplied to the water heater.
    5. Check the pump operation.
    6. If it doesn’t work, ensure wiring connections to pump.
    7. If even supply power to pump and doesn’t run it, replace the pump.
    8. If Error happens again:
    9. Verify recirculation loop length is within specification. Air purge is not enough.
    10. Too much restriction on recirculation loop.
    11. Return loops are clogged.
    12. Check the recirculation loop condition.

    Replacement Parts or Equipment

    Rheem Error Codes 61 or 99

    FAULT = Combustion Fan Failure or Fan Speed Abnormal

    1. This Error Code will go away when the condition is remedied. If Error happens again:
    2. Check the connections to the fan. Ensure all are secure.
    3. If the fan does not rotate during the ignition sequence, check for DC15~30V power at the fan connection. If DC15~30V power is present at the control, replace the fan. If the blower does not have DC15~30V power, check power at the control. If DC15~30V power is not present at the control, replace the control.
    4. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 65

    FAULT = Faulty water flow solenoid

    1. Check solenoid for buildup and clean.
    2. Replace solenoid.
    3. Ohm out solenoid valve.

    Replacement Parts or Equipment

    Error Code 66

    FAULT = Mixing Valve Error

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Turn power OFF and ON at the main power switch internal to the water heater.
    3. Check wiring connections to mixing valve. Ensure all are secure.
    4. Replace mixing valve.
    5. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 67

    FAULT = AGM Error

    1. Press the Power button to clear the Error Code. If Error happens again:
    2. Turn power OFF and ON at the main power switch internal to the water heater.
    3. Ensure fan inlet hole is completely open after turning the power OFF and ON.
    4. Check wiring connections to the AGM. Ensure all are secure.
    5. Check AGM operation.
    6. Replace AGM components.
    7. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 71

    FAULT = Gas Inlet Solenoid Valve Control Fault

    1. Check gas inlet solenoid valve wiring harness for loose or damage terminals.
    2. Ohm out solenoid valve.
    3. Replace PCB

    Replacement Parts or Equipment

    Error Code 72

    FAULT = Flame Signal Detected before Ignition

    1. This Error Code will go away when the condition is remedied. If Error happens again:
    2. Check the water heater cover. Ensure it is secure. Flame detection sensor can detect an external light source.
    3. Check flame detection sensor. Ensure connections are secure. Normal operating settings are more than 2.5DC before ignition, less than 2.5DC after ignition.
    4. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 72

    FAULT = Communication Fault with Remote Control

    1. Flush tankless to remove scale and1. Check remote control wiring for loose or damaged connections.
    2. Bypass remote control cable by connecting remote control directly to remote control terminals on PCB.
    3. Replace cable if found to be faulty.
    4. Replace remote control.
    5. Replace PCB..

    Replacement Parts or Equipment

    Error Code 73

    FAULT = DIP Switch is abnormal

    1. This Error Code will go away when the condition is remedied. If Error happens again:
    2. Check dip switches. Ensure switches match the ratings plate requirements of the water heater. See dip switch details, this manual, for default settings.
    3. If the problem persists, replace the main control..

    Replacement Parts or Equipment

    Error Code 76

    FAULT = Poor Communication

    1. This Error Code will go away when the condition is remedied. If Error happens again:
    2. Check connections from main control to display panel.
    3. If the problem persists, replace the display and/or the main control.

    Replacement Parts or Equipment

    Error Code 78

    FAULT = Cascade Communication Error

    1. NOTE: This error will only appear in a cascaded system.
    2. Turn power OFF and ON at the appliance display panel.
    3. If error reappears, ensure all cascaded appliances are powered ON.
    4. If error reappears, check Installer Mode parameter 10:Cn at among the both units.
    5. Ensure the setting as “on” in 10:Cn of Installer Mode.
    6. If error reappears, check the wire cables into the ‘Main PCB’ connector inside both units. Ensure the connection of cascade cable between both appliances.
    7. If there was no problem wiring connection, replace damaged cables.
    8. If the problem persists, replace the main control.

    Replacement Parts or Equipment

    Error Code 79

    FAULT = Fan Motor Current Fault

    1. Ensure fan motor will turn freely. (Motor will operate with a small amount of restriction.)
    2. Check fan motor for proper voltage.
    3. Replace fan motor.
    4. Replace PCB.

    Replacement Parts or Equipment

    Rheem Error Codes 80 & 81

    FAULT = Gas Cut-off Failure

    1. Ohm out all solenoid valves.
    2. Check voltage of all flame rods.
    3. Replace gas control valve.

    Replacement Parts or Equipment

    Error Code 82

    FAULT = Gas type data failure

    1. Program PCB for proper gas type.

    Replacement Parts or Equipment

    Error Code 88

    FAULT = Gas type data failure

    1. Program PCB for proper gas type.

    Replacement Parts or Equipment

    Error Code 92

    FAULT = Gas type data failure

    1. Program PCB for proper gas type.

    Replacement Parts or Equipment

    Error Code 93

    FAULT = Gas type data failure

    1. Program PCB for proper gas type.

    Replacement Parts or Equipment

    Error Code 94

    FAULT = Exhaust NTC detects Vent Temperature is High

    1. This Error Code will go away when the condition is remedied. If Error happens again:
    2. Check if dip switch High Fire setting is ON. Switches 6 and 7 should be OFF for normal operation.
    3. Check exhaust temperature sensor. Ensure connections are secure.
    4. Check sensor resistance. If resistance is zero, replace the sensor.
    5. Check exhaust vent for blockage.
    6. If the problem persists, replace the control.
    7. If the problem persists, replace the heat exchanger.

    Replacement Parts or Equipment

    Rheem Error Codes 99 or 61

    FAULT = Blocked Flue Fault

    1. Clean any blockage in heat exchanger, combustion fan, inlet filter, and exhaust flue.

    Replacement Parts or Equipment

    • Not Applicable

    No Error Code

    FAULT = Nothing happens when water is flowing through unit.

    1. Make sure unit is connected to proper power supply and circuit breakers are on.
    2. Make sure power supply inlet fuses are not blown.
    3. Clean inlet water supply filter.
    4. Ensure you have at least the minimum flow rate required to fire unit.
    5. Check for pipe dope inside water flow control turbine.
    6. On new installations ensure hot and cold water lines are not crossed.
    7. Check for bleed over. (Close cold water supply valve to water heater. Open hot water taps at fixtures. If water flows steady from hot water taps, there is a bleed over in the system.)

    Replacement Parts or Equipment

    • Not Applicable

    Error Code P1

    FAULT = Not enough water flow to operate.

    1. Increase water flow at fixture/fixtures.

    Replacement Parts or Equipment

    • Not Applicable

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