Rinnai tankless water heater / continuous flow hot water system error codes
Complete list of 40 checked codes for Rinnai tankless water heaters, with what each code means and whether you can fix it yourself.
Reference sheet from https://faultcodeindex.com/rinnai/tankless-water-heater/ (checked against Rinnai manuals).
| Code | Meaning | What you can do |
|---|---|---|
| 02 | Burner did not light during freeze protection | Safe checks first, then a pro |
| 03 | Power cut during bath fill | You can often fix it |
| 05 | Bypass flow control failure | Safe checks first, then a pro |
| 10 | Air intake, flue or condensate blockage | Safe checks first, then a pro |
| 11 | No ignition | Safe checks first, then a pro |
| 12 | Flame failure or low gas flow | Safe checks first, then a pro |
| 13 | Combustion fault | Safe checks first, then a pro |
| 14 | Overheat safety device tripped | Call a pro |
| 15 | Venturi control failure | Safe checks first, then a pro |
| 16 | Over-temperature shutdown | Safe checks first, then a pro |
| 17 | Venturi blockage | Safe checks first, then a pro |
| 18 | Gas valve adjustment limit | Call a pro |
| 19 | Electrical earth fault | Call a pro |
| 21 | Data transfer or dip switch error | Call a pro |
| 22 | Gas valve adjustment fault | Call a pro |
| 25 | Sensor fault or condensate blockage (depends on model) | Depends on your model |
| 32 | Outgoing water temperature sensor fault | Call a pro |
| 33 | Heat exchanger thermistor fault | Call a pro |
| 34 | Temperature sensor fault (depends on model) | Call a pro |
| 36 | Lower tank thermistor fault | Call a pro |
| 38 | Exhaust temperature thermistor fault | Call a pro |
| 41 | Frost protection (ambient) sensor fault | Call a pro |
| 51 | Inlet water thermistor fault | Call a pro |
| 52 | Gas modulating valve fault | Call a pro |
| 54 | High exhaust gas temperature | Safe checks first, then a pro |
| 55 | Service reminder | Safe checks first, then a pro |
| 57 | Burner overheat switch open | Call a pro |
| 58 | Secondary heat exchanger overheat | Call a pro |
| 61 | Combustion fan failure | Call a pro |
| 63 | Recirculation low flow | Call a pro |
| 65 | Water flow control failure | Safe checks first, then a pro |
| 66 | Bypass flow control fault | Call a pro |
| 70 | Control board (PCB) failure | Safe checks first, then a pro |
| 71 | Gas solenoid valve failure | Call a pro |
| 72 | Flame rod circuit error | Call a pro |
| 73 | Burner thermocouple fault | Call a pro |
| 79 | Water leak detected | Safe checks first, then a pro |
| 92 | Neutraliser end of life | Call a pro |
| LC | Scale build-up in the heat exchanger | Safe checks first, then a pro |
| SE | Cascade connection failure | Call a pro |