Rinnai 31: Burner / Flame Sensor Fault
What the Rinnai 31 error code means, what causes it, and why it's a job for a licensed BC gas technician — not a DIY reset.
Severity
Moderate — book a service visit
Gas safety first
This fault involves gas, combustion or venting. If you smell gas (rotten-egg odour), hear hissing, or feel unwell, leave the building immediately and call 911 or FortisBC at 1-800-663-9911 from outside. Do not flip switches or relight anything. For all other cases, switch the boiler off and call a licensed gas technician.
What the Rinnai 31 error code means
The flame-sensing circuit reported an abnormal reading.
On Rinnai i-Series, M-Series and Q-Series, 31 is a flame failure. It is a protective response — the boiler is telling you something needs attention, and the safe, lasting fix is a proper diagnosis rather than repeated resets.
Symptoms you may notice
- Boiler fires briefly then shuts down
- Intermittent heat or hot water
- Short-cycling with lockouts
Common causes of Rinnai 31
Why this is not a DIY fix
Loss-of-flame and false-flame faults point to the flame-rectification circuit, a dirty flame sensor, a failing gas valve, or unstable combustion. Confirming the cause needs live flame-current (microamp) readings and combustion analysis — instrumented gas work reserved for licensed technicians.
In British Columbia, gas work must be performed by a TSBC-licensed gas fitter. GasBoilers.ca — a CanroHeat division — sends Red Seal–certified, gas-licensed technicians who diagnose the true cause, repair it correctly, and verify safe operation before they leave.
How our technicians diagnose & repair it
- 1Measure flame-rectification current (microamps) during firing
- 2Clean or replace the flame-sensing electrode and check its ground path
- 3Inspect the burner and heat exchanger for sooting or fouling
- 4Verify gas pressure and re-run combustion analysis
Related Rinnai codes
Rinnai 31 — FAQ
What does the Rinnai 31 error code mean?
The flame-sensing circuit reported an abnormal reading. On Rinnai i-Series, M-Series and Q-Series, this is categorised as a flame failure.
What causes Rinnai 31?
The most common causes are: Dirty/failed flame rod; Wiring fault; Grounding issue. A licensed technician confirms which one applies before any part is replaced.
Can I fix Rinnai 31 myself?
No. Loss-of-flame and false-flame faults point to the flame-rectification circuit, a dirty flame sensor, a failing gas valve, or unstable combustion. Confirming the cause needs live flame-current (microamp) readings and combustion analysis — instrumented gas work reserved for licensed technicians. Repeatedly resetting the boiler without fixing the root cause can be unsafe and can cause further damage. Call GasBoilers.ca at 604-359-1081 for a licensed diagnosis.
Is the Rinnai 31 error code dangerous?
It can be. This fault involves combustion, gas or venting. If you ever smell gas, leave the building immediately and call 911 or FortisBC at 1-800-663-9911 from outside. Otherwise, switch the boiler off and book a licensed technician.
How much does it cost to fix Rinnai 31 in Greater Vancouver?
Cost depends on the root cause and any parts needed. We start with a flat-rate diagnostic, then quote the repair before any work begins — no surprises. Call 604-359-1081 for current pricing and same-day availability.
Look up another brand's error codes
Rinnai showing 31? We'll fix it right.
Licensed, Red Seal–certified gas technicians across Greater Vancouver. Upfront pricing, same-day service available.