Rheem Error Codes

Rheem Tankless Error 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 lists the Rheem error codes along with their possible problem and solution. Using this chart may help you diagnose and/or fix a problem you may be experiencing.

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.

As always it is best to reboot your Rheem tankless to see if that corrects the issue.
1. Unplug the water heater from power, wait about 30 seconds and plug it back in.

Rheem Tankless Error Codes
CodeFaultSolutionReplacement Parts
1LLime/Scale BuildupFlush tankless to remove buildup.Tankless Flush Kit
001 Hour continuous combustionClose all hot water taps to reset unit.
Turn off, or remove circulation pumps (unit is not designed for continuous operation with circulation systems).
Not Applicable
05Imperfect Combustion Alarm1. 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.
Not Applicable
10False flame detection1. Check all vent components for proper connections.
2. Check that nothing is blocking the flue inlet or exhaust.
3. Ensure proper venting materials were used.
4. Ensure condensation collar was installed correctly.
5. Ensure heat exchanger fins, fan, and air intake are not blocked.
Rheem Proper vent kit
11No Ignition1. Ensure you have gas to the appliance.
2. Ensure gas type and pressure is correct.
3. Bleed all air from gas lines.
4. Ensure gas line, meter, and regulator are sized properly.
5. Ensure appliance is properly grounded.
6. Check gas solenoid valves for open or short circuits.
7. Ensure igniter is operational.
8. Check igniter wiring harness for damage.
Rheem proper concentric vent kit
12Flame Failure1. 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.
Not Available
13If this code is displayedContact a dealer or qualified service technician. Not Applicable
14Overheat Wrap Fault1.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.
1. High Temperature Conversion Kit
2. Propane Commercial Conversion Kit
3. Natural Gas Conversion Kit
15Boiling Safety Device1. 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 setpoint temperature below 180F at high altitude.
Tankless Flush Kit
16Over Temperature Warning1. Check for clogged heat exchanger.
2. Check for restrictions in air flow around unit and vent terminal.
3. Check for a foreign materials in combustion chamber and/or exhaust piping.
Not Applicable
21Malfunction of Air Intake Filter Switch1. Make sure air filter door is properly seated.
2. Make sure front panel is properly installed.
Not Applicable
24Malfunction of Operational Switch1. Press max button on PCB to reset.
2. Press min button on PCB to reset.
3. Replace PCB
Replacement PCB Board RTGH-84 and 95
29Heat Exchanger Outlet Temp. Too Low1. Clean heat exchanger air inletNot Applicable
29Neutralizer is clogged.1. Check condensate line for issues.
2. Replace condensate neutralizer.
Rheem replacement neutralizer kit.
31Water Inlet Temperature Sensor Fault1. Check sensor wiring for damage.
2. Ohm out sensor
3. Check and clean scale from sensor.
4. Replace sensor.
Not Available
33Outgoing Water Temperature Sensor Fault1. Check sensor wiring for damage.
2. Ohm out sensor
3. Check and clean scale from sensor.
4. Replace sensor.
Not Available
34Combustion Air Temperature Sensor Fault1. Combustion Air
Temperature Sensor Fault
Not Available
35Improper Thermistor Connections1. Check that all thermistors are connected to proper connections on PCB.Not Applicable
51Gas Inlet Solenoid Valve Fault1. Check gas inlet solenoid valve wiring harness for loose or damage terminals.
2. Ohm out solenoid valve.
Not Applicable
52Modulating Solenoid Valve Fault1. Check modulating gas solenoid valve wiring harness for loose or damage terminals.
2. Ohm out solenoid valve.
Not Applicable
61 or 99Combustion Fan Failure1. Ensure fan motor will turn freely. (Motor will operate with a small amount of restriction.)
2. Check wiring harness to motor for damaged and/or loose connections.
3. Ohm out motor winding.
Replacement Fan Motor
65Faulty water flow solenoid1. Check solenoid for buildup and clean.
2. Replace solenoid.
3. Ohm out solenoid valve.
Not Applicable
71Gas Inlet Solenoid Valve Control Fault1. Check gas inlet solenoid valve wiring harness for loose or damage terminals.
2. Ohm out solenoid valve.
3. Replace PCB
Replacement PCB Board RTGH-84 and 95
72Communication Fault with Remote Control1. 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.
1. Replacement EZ link cable
2. Replacement Main Controller
3. Replacement Bath 1 Controller
4. Replacement PCB Board RTGH-84 and 95
79Fan Motor Current Fault1. 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.
1. Replacement Fan Motor
2. Replacement PCB Board RTGH-84 and 95
80,81Gas Cut-off Failure1. Ohm out all solenoid valves.
2. Check voltage of all flame rods.
3. Replace gas control valve.
Not Available
82Gas type data failureProgram PCB for proper gas type. 1. High Temperature Conversion Kit
2. Propane Commercial Conversion Kit
3. Natural Gas Conversion Kit
88Gas type data failureProgram PCB for proper gas type. 1. High Temperature Conversion Kit
2. Propane Commercial Conversion Kit
3. Natural Gas Conversion Kit
92Gas type data failureProgram PCB for proper gas type. 1. High Temperature Conversion Kit
2. Propane Commercial Conversion Kit
3. Natural Gas Conversion Kit
93Gas type data failureProgram PCB for proper gas type. 1. High Temperature Conversion Kit
2. Propane Commercial Conversion Kit
3. Natural Gas Conversion Kit
99Blocked Flue FaultClean any blockage in heat exchanger, combustion fan, inlet filter, and exhaust flue.Not Available
No CodeNothing 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.)
Not Aplicable
P1Not enough water flow to operate.Increase water flow at fixture/fixtures.Not Applicable