Rinnai SENSEI Code 11
No ignition. A full ignition cycle ran and no flame was established. Rinnai's list for the SENSEI starts at the gas supply — closed valves, an empty propane tank, air still in the line after installation — then the igniter and the spark electrode gap (0.138 in. / 3.5 mm), then the flame rod, all inside the sealed combustion chamber.
Call a proThe verdict
Call a licensed plumber
Confirm gas is actually reaching the house and the unit; that is the only part of the list that is safe for you. The rest is the gas train and the combustion chamber. Expect a service call around $150-300, more if the igniter, flame rod, or gas valve is replaced.
Typical cost: $150–$900
US estimate for parts and labor. Prices vary by region and by who does the work — see how we estimate costs.
What the manual says
The meaning above is transcribed from the manufacturer's diagnostic documentation for the SENSEI — not averaged across the brand.
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 16), read Aug 2026 — the manufacturer's own documentation for this exact series.
What you can safely check
Before anything else: if you smell gas, stop here, leave, and call your gas utility.
- If you smell gas at any point, stop: leave the building and call your gas utility from outside.
- Check whether other gas appliances in the house work. If nothing gas-fired runs, the supply is the problem, not the heater.
- On propane, check the tank level.
- Confirm the manual gas shut-off valve below the unit is open (handle in line with the pipe).
- Stop there. Do not open the front panel or test the igniter.
Frequently asked questions
The unit was converted between natural gas and propane. Could that be it?
It is high on the list. On the SENSEI, gas type is set by a physical orifice in the gas valve — red for propane, blue for natural gas — and by parameter 10. A conversion done without changing the orifice produces ignition faults. The newer SENSEI RX has no orifice to get wrong; it is parameter-only.
Can I keep pressing reset?
No. Each reset asks a gas appliance to try to light again with the fault still present. Two failures is the point to stop.
Code 11 on other Rinnai series
The same code number can mean something different on another series — make sure you're reading the page for your exact unit: