Rinnai tankless water heater code 02: Burner did not light during freeze protection
Tankless water heater, United States
The heater tried to fire the burner to protect itself from freezing, but the burner did not light.
This needs a licensed gas or HVAC technician. There are a few safe checks you can do first, marked below. Anything inside the unit is a job for a professional.
This involves the gas supply or burner. Only a licensed technician should open the unit or work on gas parts.
Only some models show this code. Check the list below.
What causes it
-
A gas valve is closed, air was not purged from the gas line, or inlet gas pressure is too low.
Check the gas supply is onYou can do this
- Check whether your other gas appliances, such as the cooktop, are working.
- Check the gas isolation valve to the unit is open. On most quarter-turn valves the handle sits in line with the pipe when open.
- On bottled LPG, check the cylinder is not empty and the cylinder valve is open. If you smell gas, do not use switches or flames. Leave the area and call your gas emergency line.
-
The igniter is not sparking, or the electrode or flame rod is loose, dirty or wired to the wrong rod.
-
Blocked burner orifices, debris or insects in the burner chamber, or build-up between the heat exchanger fins.
How to read this code on your unit
Booking a licensed gas or HVAC technician
Book a licensed gas or HVAC technicianlicensed gas or HVAC technician
- Turn the unit off and leave the covers on. Gas components must only be serviced by a licensed technician.
- Note the code, how often it appears, and the model and serial numbers from the rating label.
- Book a licensed gas or HVAC technician and give them those details.
Models that show this code
32 models in 7 ranges
| Range | Models |
|---|---|
| Commercial (KB) | C199i (REU-KBD3237FFUDC-US), C199e (REU-KB3237WDC-US) |
| KB | RU80i (REU-KB2530FFUD-US), RU80e (REU-KB2530WD-US), RU90e (REU-KBD2934WD-US), RU98i (REU-KB3237FFUD-US), RU98e (REU-KB3237WD-US) |
| KBD | RUC80i (REU-KBD2530FFUD-US), RUC90i (REU-KBD2934FFUD-US), RUC98i (REU-KBD3237FFUD-US) |
| KBP | RUR98i (REU-KBP3237FFUD-US), RUR98e (REU-KBP3237WD-US) |
| KCM | RUCS65i (REU-KCM2025FFU-US), RUCS75i (REU-KCM2528FFU-US), RUS65e (REU-KCM2025W-US), RUS75e (REU-KCM2528W-US) |
| Luxury (VC) | RL75i (REU-VC2528FFUD-US), RL75i(A) (REU-VC2528FFUD-US(A)), RL75e (REU-VC2528WD-US), RL75e(A) (REU-VC2528WD-US(A)), RL94i (REU-VC2837FFUD-US), RLX94i (REU-VC2737FFUD-US), RL94e (REU-VC2837WD-US) |
| Value (VC) | V53e (REU-VAM1620W-US), V53De (REU-AM1620WD-US), V65i (REU-VC2025FFU-US), V65e (REU-VC2025W-US), V75i (REU-VC2528FFU-US), V75e (REU-VC2528W-US), V94i (REU-VC2837FFU-US), V94Xi (REU-VC2737FFU-US), V94e (REU-VC2837W-US) |
Where this comes from
- Troubleshooting tankless water heater diagnostic codes (100000652), non-SENSEI and SENSEI series , page 4
Checked against the manufacturer's manual on 9 October 2026.
Other Rinnai tankless water heater codes
| Code | Meaning | What you can do |
|---|---|---|
| 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 |
See all ignition failure codes on tankless water heaters across brands.