Rinnai tankless water heater codes
A tankless water heater shows its fault as a number or letter code on the unit display or on the wired remote controller, and some models keep a short history of past codes. Write the code down exactly as shown before you reset the unit, and check the rating plate for the model number, because the same number can mean different things between series.
Models covered: RL75i, RL94i.
All 17 codes
02No burner operation during freeze protection mode (pro repair)03Power interruption during bath fill (DIY)10Air supply or exhaust blockage (pro repair)11No ignition (pro repair)12Flame failure (pro repair)14Thermal fuse (pro repair)16Over temperature warning (pro repair)31Burner sensor error (pro repair)32Outgoing water temperature sensor fault (pro repair)33Heat exchanger outgoing temperature sensor fault (pro repair)34Combustion air temperature sensor fault (pro repair)52Modulating solenoid valve signal abnormal (pro repair)61Combustion fan failure (pro repair)65Water flow servo faulty (pro repair)72Flame sensing device fault (pro repair)73Burner sensor circuit error (pro repair)LCScale build-up in heat exchanger (DIY)
About Rinnai codes
Rinnai makes gas tankless water heaters that report faults as two-digit diagnostic codes on the unit or the wired controller. The codes are shared across its range, but troubleshooting steps vary by series, so use the series in your manual. The codes apply to model numbers such as RL75i and RL94i; check the label on your unit to confirm yours.