Rinnai error code 15
Venturi control fault. Code 15 means the same thing on all 2 Rinnai series documented here — but the fix, and what it costs, is still worth reading for your exact unit.
What code 15 means on each Rinnai series
| Series | What it means | Verdict | Typical cost |
|---|---|---|---|
| SENSEI | Venturi control fault | Call a pro | $0–$1,100 |
| SENSEI RX | Venturi control fault | Call a pro | $0–$1,100 |
Each series links to the full page: what the manufacturer's manual says for that generation, what you can safely check yourself, and what the repair should cost.
How much the answer changes between series
Every Rinnai series that documents code 15 routes it the same way: a professional. That is unusual enough to be worth saying, because on this brand the same number often means different work on different generations. Here it does not — so you can act on this page without first establishing which unit you own.
The cost is documented the same way across all 2 series: $0–$1,100, depending on which of the manufacturer's causes turns out to be yours.
What to check first, whatever your series
These checks are on the manufacturer's list for every Rinnai series that reports code 15, so they are safe to work through before you have identified your exact unit. They also cost nothing.
- If you smell gas at any point, leave and call your gas utility from outside.
If none of those explains it, go to your own series above — the remaining checks differ by generation, and that is the whole reason this page exists.
Which Rinnai do you have?
The model number is on the rating label on the unit itself. Match it against the list below — or use the full model-number decoder.
Where this comes from
Source: Rinnai Troubleshooting Tankless Water Heater Diagnostic Codes (100000652) (p. 26), read Aug 2026 — the manufacturer's own documentation for this Rinnai range.
The same number on other brands
Code 15 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 15
Everything the 2 Rinnai series point at for this code, in one list. A part named here is one the manufacturer's own procedure reaches for.