| Rinnai | No Code | Nothing happens when water flow is activated
● Clean inlet water supply filter. Be sure to turn off water to the unit.
● Verify you have minimum flow rate needed to fire the unit.
● Make sure hot and cold water valves are open.
● Make sure hot and cold water lines are not reversed. |
| Rinnai | Error Code 00 or LC | Scale builds up in heat exchanger
Do not ignore this code just because it allows the tankless water heater to continue running. Excess scale buildup can irreparably damage the heat exchanger.
● Flush the heat exchanger according to the instructions in the owner’s manual.
● Replace the heat exchanger. |
| Rinnai | Error Code E02 | No burner operation during freeze protection mode |
| Rinnai | Error Code E03 | Power interruption during bath fill
Water will not flow when power returns—turn off all hot water faucets/taps. Press on/off button twice. |
| Rinnai | Error Code E05 | Bypass Servo
Turn off power supply to unit, reapply power. Fire up unit. If code 05 reappears, replace the bypass valve. |
| Rinnai | Error Code E10 | Air Supply or Exhaust Blockage
Inspect the entire vent system inside/outside the installation location. Check for clearance issues, improper venting or materials used, etc.
Inspect the vent system to ensure all clearances around vent terminations were met. Improper clearances will result in recirculation of combustion gases.
Verify vent terminals are installed with the proper clearance from overhangs, grade, obstructions, walls, porches, etc. See venting instructions for proper clearance requirements.
The fan may be blocked or no longer working.
If the error code 10 still shows, contact Blue Conservation at 484-469-0718 to troubleshoot and address the Rinnai code 10. |
| Rinnai | Error Code E11 | No Ignition
This is often a gas issue.
● Is the gas on? You can confirm by turning on another appliance.
● Has the unit been running without issue for some time? What could have changed? Has there been construction in the area that could have impacted the gas pressure?
● Disconnect EZConnect™ or MSA controls to see if you can isolate the problem.
● Ensure the igniter is operational. Check the wiring harness for damage.
If you are not familiar with both wiring and gas, you should call or text Blue Conservation at 484-469-0718 to address a Code 11. |
| Rinnai | Error Code E12 | Flame failure
This can be gas, air, or spark. Review the Code 10 checklist. If those don’t address the issue, continue to the following.
● Check the power supply. Any loose connections?
● Is the flame rod wire connected? Any problems with carbon buildup on the flame rod?
If you are not familiar with both wiring and gas, you should call or text Blue Conservation at 484-469-0718 to address a Code 12. |
| Rinnai | Error Code E14 | Thermal fuse or Overheat
Code 14 is an indication of overheating and should be taken seriously. You can check the following to help address the issue:
● Check for air flow restrictions.
● Is water pressure low? This can cause problems related to short-cycling and overheating.
● Flush the heat exchanger following the instructions on the owner’s manual.
● Check dip switches.
● Obstructions can cause problems with thermal fuse function. Check the venting to make sure there are no obstructions.
● Inspect the exterior of the heat exchanger. Is there any scale buildup? Does the heat exchanger look worn, discolored, or damaged?
● Inspect all the components in the cabinet for signs of excessive heat damage.
If you are not familiar with both wiring and gas, you should call or text Blue Conservation at 484-469-0718 to address a Code 14. |
| Rinnai | Error Code E15 | Venturi Control
● Follow directions for error code 10, vent blockage.
● Replace gas valve assembly.
● Clear diagnostic code by power-cycling the unit.
If you are not familiar with both wiring and gas, you should call or text Blue Conservation at 484-469-0718 to address a Code 15. |
| Rinnai | Error Code E16 | Over temperature warming
Safety shutdown because unit is too hot. This is caused by poor airflow.
● Make sure that the combustion chamber, exhaust piping, and heat exchanger are clear.
● This could also be a result of poor water flow. Flush the heat exchanger following instructions in the owner’s manual. |
| Rinnai | Error Code E17 | Venturi Blockage
● Follow directions for error Code 10, vent blockage.
● Ensure venturi is not blocked.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address a Code 17. |
| Rinnai | Error Code E19 | Electrical Grounding
All components should be checked for an electrical short by a qualified technician. |
| Rinnai | Error Code E21 | Data Transfer Error
● Be sure the data was transferred correctly if a PC board was replaced.
Please call or text Blue Conservation at 484-469-0718 to schedule a professional service call to address Code 21. |
| Rinnai | Error Code E25 | Condensate Trap Error
Condensate trap is full. Check drain for blockage. |
| Rinnai | Error Code E31 | Burner Sensor Error
Measure resistance of sensor and replace if needed. |
| Rinnai | Error Code E32 | Outgoing Water Temperature Sensor Fault
Check sensor wiring for damage and clean scale buildup. If needed, replace the sensor. |
| Rinnai | Error Code E33 | Heat Exchanger Outgoing Temperature Sensor Fault
Check sensor wiring for damage and clean scale buildup. If needed, replace the sensor. |
| Rinnai | Error Code E34 | Combustion Air Temperature Sensor Fault
Check sensor wiring for damage and clean scale buildup. If needed, replace the sensor. |
| Rinnai | Error Code E38 | Exhaust Thermistor
● Check sensor wiring to see if it has been disconnected or damaged.
● Check resistance or voltage of sensor.
● Clean or replace sensor.
Please call or text Blue Conservation at 484-469-0718 to schedule a professional service call to address Code 38. |
| Rinnai | Error Code E41 | Outside Temperature Sensor
Check sensor wiring for damage and clean scale buildup. If needed, replace the sensor. |
| Rinnai | Error Code E51 | Inlet Water Temperature Sensor
Check sensor wiring for damage and clean scale buildup. If needed, replace the sensor. |
| Rinnai | Error Code E52 | Gas Valve/Modulating Solenoid Valve Signal Abnormal
Check modulating gas solenoid valve wiring harness for loose or damaged terminals. Replace if needed. |
| Rinnai | Error Code E54 | High Exhaust Gas Temperature
● Make sure heat fins are not blocked.
● Check heat exchanger surface to see if there are any hot spots. Heat exchanger may need to be descaled if there is lime scale buildup.
● Confirm inlet water temperature and make sure it’s not too high.
● Power-cycle unit to clear the code.
● Make sure condensate is not blocked. |
| Rinnai | Error Code E57 | Burner (Bi-Metal Sensors/Thermal Fuse Harness)
Check for continuity through bi-metal sensors located at the top of the heat exchanger at white plastic connector containing red and white wires. |
| Rinnai | Error Code E58 | Secondary Heat Exchanger
There is scale buildup in the secondary heat exchanger. Perform a descaling flush according to the instructions in the owner’s manual. |
| Rinnai | Error Code E61 | Combustion Fan Failure
● Examine the combustion fan to verify that it can turn freely.
● Examine all wiring connections for damage.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 61. |
| Rinnai | Error Code E63 | Recirculation Low Flow
● Check pump speed settings and confirm flow rate during recirculation.
● Make sure inlet filter is clean and is not clogged.
● Check to be sure the pump is receiving the correct voltage.
● Purge the recirculation line and make sure it is free of air.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 63. |
| Rinnai | Error Code E65 | Water Flow Control Fault
● The water flow control valve has failed to close. Contact a plumber immediately.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 65. |
| Rinnai | Error Code E66 | Flow Servo
● Check resistance voltage reading.
● Make sure wire harness is not damaged or wet.
● Next step is to replace the PC board. |
| Rinnai | Error Code E70 | Sensor Harness Connection
● Confirm that dip switch settings are correct.
● May need to replace the PC board.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 70. |
| Rinnai | Error Code E71 | Solenoid Valve Circuit Fault
You probably need to replace the solenoid valve.
● Check the wiring harness to all solenoids.
● Replace the PC board.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 71. |
| Rinnai | Error Code E72 | Flame Sensing Device Fault
● Check to see if the flame rod is touching flame when the unit fires. Inspect burner chamber for excess buildup.
● Examine flame rod wiring for damage.
● Clean the flame rod with sandpaper.
● Replace flame rod.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 72. |
| Rinnai | Error Code E73 | Burner Sensor Circuit
Check sensor wiring and PC board for damage and replace sensor if needed.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 73. |
| Rinnai | Error Code E79 | Water Leakage Detected
● Turn off water and gas supply and disconnect power to the unit.
● Inspect the unit for a leak and dry area around the moisture-sensing element.
● It is important to determine the source of the water.
Please call or text Blue Conservation at 484-469-0718 to schedule a service call with a professional to address Code 79. |
| Rinnai | LC | Scale Buildup Detected in the Heat Exchanger
● Perform descaling flush on the heat exchanger.
● Reset LC code and contact Rinnai. |
| Rinnai | 55 | “Service Soon” Alert
This is not an error code—the “55” is displayed based on parameter settings. It can be activated to appear at specific intervals.
● 55 indicates it is time to perform service/planned maintenance. |
| Rinnai | FF | Maintenance Indicator
The FF is known as a “Field Flag” and is added by a technician to track error code history. |
