No flame (burner lit, then flame lost or not sensed)
Displayed as: 12
Rinnai's RU series installation and operation manual lists diagnostic code 12 as "No Flame". The manual's checks are: confirm the gas is turned on at the water heater, meter or cylinder; on propane, confirm there is gas in the tank; ensure the flame-rod wire is connected; ensure the gas type and inlet gas pressure are correct; and bleed all air from the gas lines.
If you smell gas
- Stop what you are doing. Do not use phones, switches, matches or anything that can spark inside.
- Go outside and leave the door open behind you.
- Call the FortisBC 24-hour emergency line at 1-800-663-9911 or dial 911.
Only after that, call CANRO about the water heater. Official guidance: FortisBC gas leaks and odour.
Applies to
This code and wording come from manual 100000467 for the RU series (RU130i to RU199i, indoor and outdoor). The cross-series document 100000652 applies the same code across SENSEI and non-SENSEI generations.
- Rinnai SENSEI RU (Super High Efficiency Plus condensing)
- Rinnai RU130iN
- Rinnai RU160iN
- Rinnai RU180iN
- Rinnai RU199iN
Control platform: Rinnai PC board with digital controller display. Source manual: 100000467 (rev. 07 on rinnai.ca) (2020–2021).
Why a code is not a diagnosis
Where code 11 means the burner never lit, code 12 means the burner lit and then the flame went out or the flame signal was lost. The manual's checks cover the supply side (gas on, propane present, correct pressure) and the sensing side (flame-rod wire connected, air bled from new lines). A fouled flame rod, poor combustion or a failing gas valve can produce the same code, which is why on-site testing follows the checks.
Safe things to observe
- Check whether other gas appliances work, which points to supply rather than the heater.
- Confirm the unit has power and note whether the code returns immediately after a reset or after a period of running.
- On propane, check the tank gauge; on natural gas, check that the meter valve has not been closed.
Do not
- Do not repeatedly reset the unit to force ignition.
- Do not adjust gas pressure, change the orifice or touch the flame rod or igniter.
- Do not bypass any safety control to hold the burner on.
How professional service helps
- A licensed gas fitter measures inlet and manifold gas pressure and confirms the fuel type.
- The flame-rod circuit and wire are tested, and the rod is cleaned if fouled.
- Air is purged from new or reopened gas lines before the unit is returned to service.
Diagnostic visit
Repair visits carry a diagnostic service fee that CANRO states is credited toward the repair if you proceed. The amount is confirmed by phone; it is not published. Source, checked September 7, 2026.
Where CANRO provides on-site service
On-site service is currently offered across Metro Vancouver: Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Delta, Langley, Port Moody, Port Coquitlam, Maple Ridge, Pitt Meadows, White Rock, Tsawwassen; plus Anmore, Belcarra, Lions Bay, Bowen Island, Abbotsford with travel or ferry arrangements confirmed by phone. Everything else on this site is reference information you can use anywhere in Canada.
Frequently asked questions
What is the difference between codes 11 and 12?
Code 11 is No Ignition (the burner never lit); code 12 is No Flame (the burner lit and then the flame was lost or not sensed). Both start with the gas-supply checks.
Can a fouled flame rod cause code 12?
Yes. A dirty or disconnected flame rod loses the flame signal even when the burner is firing. Cleaning and testing the rod circuit is technician work.
Does code 12 mean a gas leak?
Not by itself. If you smell gas, leave and call FortisBC at 1-800-663-9911 or 911; otherwise code 12 points to supply, flame-sensing or combustion causes a technician confirms on site.
Locked out with no hot water? Call with the code ready.
The brand, model and this code are passed along when you request service online, so the technician arrives prepared.
On-site service in Metro Vancouver, BC. Call to check availability.
Sources and verification
- Rinnai RU series Installation and Operation Manual, section 5.6 Diagnostic Codes · 100000467 · accessed September 7, 2026
- Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes · 100000652 · accessed September 7, 2026
Facts checked September 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.