Rinnai SENSEI RX Code 11
No ignition. The heater ran a full ignition cycle and never established a flame. Rinnai's SENSEI RX list starts with the gas supply itself — closed valves, an empty propane tank, air still in the line after an installation — and then moves to the igniter, the spark electrode gap, and the flame rod, all of which sit inside the sealed combustion chamber.
Call a proThe verdict
Call a licensed plumber
Check that gas is actually reaching the house and the unit; that is the one part of Rinnai's list you can do safely. Everything else — igniter, electrode, gas pressure, gas-type parameter — is inside the combustion chamber or on the gas train and belongs to a licensed professional. Expect a service call in the $150-300 range, 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 RX — 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 problem is the supply, not the heater.
- On propane, check the tank level — an empty or undersized tank is the first thing Rinnai lists.
- 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, test the igniter, or adjust gas settings.
Frequently asked questions
What is the difference between code 11 and code 12?
Code 11 means the unit never lit. Code 12 means it lit and then lost the flame, or could not prove the flame was there. They share causes — a dirty flame rod, low gas pressure — but 11 points harder at ignition and 12 at flame detection.
It happened right after the unit was installed or converted to propane. Coincidence?
Unlikely. Rinnai lists air still in the gas line after installation and a wrong gas-type parameter as causes. On a SENSEI RX the gas type parameter can only be changed within 20 minutes of a power reset, which is why this is an installer callback, not a DIY fix.
Can I just keep pressing reset?
No. Each reset asks a gas appliance to try to light again with the fault still present. If it fails twice, leave it off and get it looked at.