Rinnai tankless water heater error codes
Rinnai is one of the most widely installed tankless water heater brands in the US. Its diagnostic codes are grouped by series generation — SENSEI RX/CX, SENSEI, and the older non-SENSEI models — and the same two-digit number can point at a different component depending on which generation is on the wall. Every code below is read from Rinnai's own diagnostic documentation for the exact series, not averaged across the brand.
Pick your series below — Rinnai code meanings are documented per series, because the same number can point to a different fault on a different generation.
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Non-SENSEI
31 documented codes
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RH180 Hybrid
20 documented codes
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SENSEI
27 documented codes
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SENSEI RX
31 documented codes
Codes documented on more than one Rinnai series
Pick a number to see what it means on each series side by side — useful when you know the code but not the generation.
Not sure which series you own? The model-number decoder matches the number on your rating label to the right table.
All Rinnai codes in one table
| Code | Series | Error | Verdict |
|---|---|---|---|
| 02 | Non-SENSEI | No burner operation during freeze protection | Call a pro |
| 03 | Non-SENSEI | Power interruption during bath fill | DIY fix |
| 05 | Non-SENSEI | Bypass flow control device fault | Part replacement |
| 10 | Non-SENSEI | Air supply or exhaust blockage | Call a pro |
| 11 | Non-SENSEI | No ignition | Call a pro |
| 12 | Non-SENSEI | Flame failure | Call a pro |
| 14 | Non-SENSEI | Overheat switch or thermal fuse tripped | Call a pro |
| 16 | Non-SENSEI | Outlet water temperature too high | Call a pro |
| 19 | Non-SENSEI | Electrical grounding fault | Call a pro |
| 25 | Non-SENSEI | Condensate pump fault or blocked condensate drain | DIY fix |
| 31 | Non-SENSEI | Burner thermocouple out of range | Call a pro |
| 32 | Non-SENSEI | Outgoing water temperature thermistor fault | Part replacement |
| 33 | Non-SENSEI | Heat exchanger thermistor fault | Part replacement |
| 34 | Non-SENSEI | Combustion air temperature thermistor fault | Call a pro |
| 38 | Non-SENSEI | Exhaust gas temperature sensor fault | Call a pro |
| 41 | Non-SENSEI | Freeze protection sensor fault | Part replacement |
| 51 | Non-SENSEI | Inlet water temperature thermistor fault | Part replacement |
| 52 | Non-SENSEI | Modulating solenoid valve (POV) signal fault | Call a pro |
| 54 | Non-SENSEI | Exhaust gas temperature too high | Call a pro |
| 57 | Non-SENSEI | Burner overheat bi-metal switch tripped | Call a pro |
| 58 | Non-SENSEI | Secondary heat exchanger switch tripped | Call a pro |
| 61 | Non-SENSEI | Combustion fan motor fault | Call a pro |
| 63 | Non-SENSEI | Recirculation low flow | DIY fix |
| 65 | Non-SENSEI | Water flow control valve fault | Part replacement |
| 70 | Non-SENSEI | PC board fault | Call a pro |
| 71 | Non-SENSEI | SV0-SV3 solenoid valve fault | Call a pro |
| 72 | Non-SENSEI | Flame rod fault | Call a pro |
| 73 | Non-SENSEI | Burner thermocouple fault | Call a pro |
| 79 | Non-SENSEI | Water leakage detected | Call a pro |
| FF | Non-SENSEI | Maintenance performed marker | DIY fix |
| LC | Non-SENSEI | Scale build-up in the heat exchanger | DIY fix |
| 05 | RH180 Hybrid | Air screen restricted | DIY fix |
| 07 | RH180 Hybrid | Circulation flow below 2.1 GPM | DIY fix |
| 10 | RH180 Hybrid | Air supply or exhaust blockage | Call a pro |
| 11 | RH180 Hybrid | No ignition | Call a pro |
| 12 | RH180 Hybrid | No flame | Call a pro |
| 13 | RH180 Hybrid | Combustion fault | Call a pro |
| 14 | RH180 Hybrid | Thermal fuse triggered | Call a pro |
| 16 | RH180 Hybrid | Over temperature warning | Call a pro |
| 30 | RH180 Hybrid | Flammable vapour sensor fault | Call a pro |
| 31 | RH180 Hybrid | Burner sensor fault | Call a pro |
| 32 | RH180 Hybrid | Heat exchanger outgoing temperature sensor fault | Call a pro |
| 35 | RH180 Hybrid | Tank temperature sensor fault | Call a pro |
| 38 | RH180 Hybrid | Carbon monoxide or flammable vapour sensor fault | Call a pro |
| 52 | RH180 Hybrid | Modulating solenoid valve signal fault | Call a pro |
| 61 | RH180 Hybrid | Combustion fan fault | Call a pro |
| 63 | RH180 Hybrid | Circulation flow below 1.3 GPM | DIY fix |
| 71 | RH180 Hybrid | Solenoid valve circuit fault | Call a pro |
| 72 | RH180 Hybrid | Flame sensing device fault | Call a pro |
| 73 | RH180 Hybrid | Burner sensor circuit fault | Call a pro |
| FE | RH180 Hybrid | Flammable vapours detected | Emergency — stop |
| 03 | SENSEI | Power interruption during bath fill | DIY fix |
| 05 | SENSEI | Bypass flow control device fault | Part replacement |
| 10 | SENSEI | Air supply or exhaust blocked, or the condensate trap is full | Call a pro |
| 11 | SENSEI | No ignition | Call a pro |
| 12 | SENSEI | Flame failure | Call a pro |
| 14 | SENSEI | Overheat sensor or thermal fuse tripped | Call a pro |
| 15 | SENSEI | Venturi control fault | Call a pro |
| 16 | SENSEI | Outlet water temperature too high | Call a pro |
| 17 | SENSEI | Venturi blockage | Call a pro |
| 19 | SENSEI | Electrical grounding fault | Call a pro |
| 21 | SENSEI | Data transfer error | Call a pro |
| 25 | SENSEI | Condensate pump fault or blocked condensate drain | DIY fix |
| 32 | SENSEI | Outgoing water temperature thermistor fault | Part replacement |
| 33 | SENSEI | Heat exchanger thermistor fault | Part replacement |
| 38 | SENSEI | Exhaust gas temperature sensor fault | Call a pro |
| 41 | SENSEI | Freeze protection sensor fault | Part replacement |
| 51 | SENSEI | Inlet water temperature thermistor fault | Part replacement |
| 52 | SENSEI | Gas valve fault | Call a pro |
| 54 | SENSEI | Exhaust gas temperature too high | Call a pro |
| 61 | SENSEI | Combustion fan motor fault | Call a pro |
| 63 | SENSEI | Recirculation low flow | DIY fix |
| 65 | SENSEI | Water flow control valve fault | Part replacement |
| 70 | SENSEI | PC board fault | Call a pro |
| 71 | SENSEI | Gas solenoid valve fault | Call a pro |
| 72 | SENSEI | Flame rod fault | Call a pro |
| FF | SENSEI | Maintenance performed marker | DIY fix |
| SS | SENSEI | Service soon reminder | DIY fix |
| 03 | SENSEI RX | Power interruption during bath fill | DIY fix |
| 10 | SENSEI RX | Air supply or exhaust blocked, or the condensate trap is full | Call a pro |
| 11 | SENSEI RX | No ignition | Call a pro |
| 12 | SENSEI RX | Flame failure | Call a pro |
| 14 | SENSEI RX | Overheat sensor or thermal fuse tripped | Call a pro |
| 15 | SENSEI RX | Venturi control fault | Call a pro |
| 16 | SENSEI RX | Outlet water temperature too high | Call a pro |
| 17 | SENSEI RX | Venturi blockage | Call a pro |
| 18 | SENSEI RX | Gas valve adjustment limit reached | Call a pro |
| 19 | SENSEI RX | Electrical grounding fault | Call a pro |
| 21 | SENSEI RX | Data transfer error | Call a pro |
| 22 | SENSEI RX | Gas valve adjustment fault | Call a pro |
| 25 | SENSEI RX | Condensate pump fault or blocked condensate drain | DIY fix |
| 32 | SENSEI RX | Outgoing water temperature thermistor fault | Part replacement |
| 33 | SENSEI RX | Heat exchanger thermistor fault | Part replacement |
| 34 | SENSEI RX | Lime detecting thermistor fault | Part replacement |
| 38 | SENSEI RX | Exhaust gas temperature sensor fault | Call a pro |
| 41 | SENSEI RX | Freeze protection sensor fault | Part replacement |
| 51 | SENSEI RX | Inlet water temperature thermistor fault | Part replacement |
| 52 | SENSEI RX | Gas valve fault | Call a pro |
| 54 | SENSEI RX | Exhaust gas temperature too high | Call a pro |
| 61 | SENSEI RX | Combustion fan motor fault | Call a pro |
| 63 | SENSEI RX | Recirculation low flow | DIY fix |
| 65 | SENSEI RX | Water flow control valve fault | Part replacement |
| 66 | SENSEI RX | Bypass flow servo fault | Part replacement |
| 70 | SENSEI RX | PC board fault | Call a pro |
| 71 | SENSEI RX | Gas solenoid valve fault | Call a pro |
| 72 | SENSEI RX | Flame rod fault | Call a pro |
| FF | SENSEI RX | Maintenance performed marker | DIY fix |
| LC | SENSEI RX | Scale build-up lockout | DIY fix |
| SS | SENSEI RX | Service soon reminder | DIY fix |
Each code links to a full page: what the manual says for that exact series, the likely fix, and what it should cost.