Rinnai tankless water heater code 11
No ignition. Code 11 means the same thing on all 4 Rinnai series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code 11 means on each Rinnai series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| Non-SENSEI | No ignition | Call a pro | $150–$900 |
| RH180 Hybrid | No ignition | Call a pro | $0–$900 |
| SENSEI | No ignition | Call a pro | $150–$900 |
| SENSEI RX | No ignition | Call a pro | $150–$900 |
Each row opens the full page for that generation. We hold manuals for Non-SENSEI, RH180 Hybrid, SENSEI and SENSEI RX, and each one gets its own reading of code 11 — what Rinnai documents, what you can safely check yourself, and what the repair should cost.
What each manual actually says
The table above compares 4 series in four columns, which is enough to route you and not enough to explain anything. This is the Rinnai wording behind each row, one entry per manual, so you can see where the 4 readings of code 11 agree and where they part company.
Non-SENSEI — No ignition
The heater called for heat, ran its ignition sequence, and never established a flame. On this generation Rinnai's checklist starts with the gas supply and gas type, moves to the spark at the igniter and the condition and tightness of the electrode and flame rod, and then goes to inlet gas pressure, venting and combustion. A loose flame rod — what Rinnai calls a floating flame rod — will produce a code 11 or a code 12 on these units.
RH180 Hybrid — No ignition
The burner did not light. Rinnai's checklist for the RH180 is a gas and ignition list from top to bottom: gas turned on at the heater, meter or cylinder, appliance grounding, gas type and pressure, gas line and meter sizing, air bled from the lines, dip switch settings, the igniter and its wiring harness, the gas solenoid valves, and finally the burners themselves, seated properly and free of condensation or debris. Everything after the first item is marked licensed professional only.
SENSEI — 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.
SENSEI RX — 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.
Does it matter which Rinnai you have?
Non-SENSEI, RH180 Hybrid, SENSEI and SENSEI RX all route code 11 the same way: a professional, at $0–$900. That makes it one of the Rinnai numbers you can act on before working out which unit you own.
Which Rinnai do you have?
On the 4 series that report code 11, the model number on the rating label starts C, RC, RU, RUC and RUR — match yours against the 78 listed below. You can also use the full model-number decoder.
Where this comes from
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 16), read Aug 2026 — the manufacturer's own documentation for this Rinnai range.
Source: Rinnai RH180 Operation and Installation Manual (100000319) (p. 35), read Sep 2026 — the manufacturer's own documentation for this Rinnai range.
The same number on other brands
Code 11 is not a standard across the industry — every manufacturer publishes its own table. If your unit is not a Rinnai, this number means something else entirely:
Parts, guides and symptoms behind code 11
Code 11 on these 4 Rinnai series points at 3 parts and 3 symptoms, each named by the manufacturer's own procedure for this code.