Rinnai Boiler Error Codes — I-Series & M-Series Reference
Complete error code guide for Rinnai I-Series and M-Series condensing boilers. The LC scale warning, Code 12, Code 14, and more — explained for Metro Vancouver homeowners.
Understanding Rinnai's Error Code System
Rinnai I-Series and M-Series condensing boilers display fault codes as numeric codes (11, 12, 14, 16, etc.) or the special LC alphanumeric warningon the unit's front LED panel. There is an important distinction between the LC code and all other Rinnai fault codes:
- LC (Lime/Scale Warning) — This is Rinnai's unique maintenance alert code. The boiler continues to operatewhen LC is displayed. Rinnai's control system calculates an estimated scale accumulation based on operating hours and the water hardness setting configured at installation. When LC appears, descaling is overdue. Many BC homeowners do not realise that LC is the precursor to Code 14 thermal fuse failure — which requires a more expensive repair.
- Numeric fault codes (11–65) — These are hard faults that lock out the boiler. The unit will not restart until the fault is resolved and a manual reset is performed using the button on the front panel.
In Metro Vancouver, Code LC and Code 14 together make up the single most common Rinnai service scenario we respond to — particularly in Surrey, Langley, and parts of Richmond where water mineral content is higher. Annual descaling service is the most cost-effective way to prevent Code 14 entirely.
If you detect gas odour when a fault code appears, do not reset the boiler. Evacuate the space and call FortisBC at 1-800-663-9911. Only call a technician once the gas utility confirms the area is safe.
Rinnai Error Code Reference Table
Covering Rinnai I-Series (I060CN through I199CN) and M-Series condensing boilers. Code descriptions may vary slightly by model year.
| Code | Name | Meaning | Common Cause | DIY Check? | Lockout? | Urgency |
|---|---|---|---|---|---|---|
| LC | Lime / Scale Warning | The boiler has calculated that limescale accumulation in the heat exchanger has likely reached a level requiring service. The unit continues to operate but is warning of reduced efficiency and risk of Code 14. | Limescale buildup from dissolved minerals in the heating system water. More common in Surrey, Richmond, and Langley water zones. | No — descaling requires chemical flushing by a certified technician. Ignoring LC leads to Code 14 thermal fuse failure. | No — runs | Moderate |
| 11 | No Ignition Spark | The ignition electrode is not producing a spark during the ignition sequence. | Cracked igniter ceramic, failed ignition module, or wiring fault to the igniter. | No — electrode inspection and ignition circuit testing required. | Yes | High |
| 12 | Flame Failure | The boiler established ignition but the flame dropped out during operation. | Fluctuating gas supply pressure, deteriorating gas valve, or fouled flame sensor. | Partial — single reset permitted. Verify gas supply is on. Repeat Code 12 requires a technician. | Yes | High |
| 14 | Thermal Fuse Tripped | The heat exchanger overheated and the one-time thermal fuse has opened permanently. The boiler cannot operate until the fuse is replaced. | Almost always caused by an unaddressed LC scale warning — scale acts as insulation, causing the heat exchanger to overheat. | No — the thermal fuse is a one-shot device and cannot be reset. Requires replacement plus mandatory descaling to prevent recurrence. | Yes | High |
| 16 | Overheating | The boiler temperature exceeded the safety high-limit setpoint. | Restricted system water flow, seized circulator pump, or stuck-closed zone valves. | No — identify and correct flow restriction before resetting to prevent secondary heat exchanger damage. | Yes | High |
| 31 | Bath / Inlet Temperature Sensor Fault | The incoming water temperature sensor is reading outside its expected range. | Sensor failure, wiring fault, or sensor connector corrosion from damp installation environments. | No — sensor resistance testing required. | Yes | Moderate |
| 32 | Outgoing Temperature Sensor Fault | The outgoing (outlet) water temperature sensor is reporting an abnormal value. | Sensor failure, wiring fault, or actual abnormal outlet temperature from flow restriction. | No — requires sensor test to distinguish between sensor fault and actual temperature condition. | Yes | Moderate |
| 51 | Gas Valve Fault | The gas valve solenoid has not responded as expected during ignition or operation. | Gas valve solenoid failure, wiring fault to valve, or debris obstructing valve operation. | No — gas valve work requires a Red Seal–licensed gas fitter. | Yes | High |
| 61 | Fan Motor Fault | The combustion fan motor is not reaching required speed or has failed to start. | Fan motor bearing wear, obstructed fan wheel, or failed motor capacitor. | No — fan motor speed measurement and inspection required. | Yes | High |
| 65 | Water Flow Switch Fault | The domestic hot water or system flow switch is not detecting flow as expected. | Fouled flow switch paddle from scale or debris, failed switch, or actual low-flow condition. | No — flow switch inspection and replacement required if fouled or failed. | Yes | Moderate |
Same-Day Rinnai Repair in Metro Vancouver
Our Red Seal–certified technicians carry Rinnai OEM parts including thermal fuse kits, flow switches, and fan motor assemblies. LC descaling and Code 14 repairs are completed same day across Greater Vancouver in most cases.
Call 604-359-1081Related Rinnai & Boiler Resources
Rinnai LC warning or Code 14? We fix it — and prevent it coming back.
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