Rinnai Rinnai RE180iN RE Series Non-Condensing Tankless Water Heater 12 Error Fix: Flame Failure

Error code 12 on the Rinnai Rinnai RE180iN RE Series Non-Condensing Tankless Water Heater means: Flame Failure. The burner flame was established but extinguished during operation. The unit successfully ignited and was heating water, but the flame sensing rod stopped detecting flame before the user closed the hot water tap. Error 12 typically indicates an intermittent issue: (1) Wind interference — strong gusts at the vent termination can blow out the flame. Install a wind-resistant vent cap or relocate the vent termination away from prevailing winds. (2) Fluctuating gas pressure — gas supply pressure dropping during operation, possibly from another high-demand gas appliance (furnace, stove) starting up simultaneously. Have a technician check dynamic gas pressure while the unit is firing. (3) Dirty flame rod — even a partially fouled flame rod can cause intermittent loss of flame signal. Clean the rod. (4) Failing gas valve — the gas valves may be closing intermittently due to an electrical fault. (5) Condensation on the flame rod — in high-humidity conditions, condensation on the flame rod can cause a momentary loss of signal. If error 12 occurs repeatedly, investigate all of the above systematically.

The most successful fix is "Test Gas Pressure and Replace Gas Valve if Needed" (hard difficulty, ~90 minutes). Estimated DIY cost: $0-$20. HomeMD has 2 community-ranked fixes for this error.

This error is rated critical severity. It is generally not urgent and can often be resolved with a simple DIY fix.

Yes — the top-ranked community fix ("Test Gas Pressure and Replace Gas Valve if Needed") is rated hard difficulty and takes about 90 minutes. Tools needed: T20 Torx screwdriver, Manometer, Leak detection solution, Multimeter.

DIY cost: $0-$20. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

The Rinnai Rinnai RE180iN RE Series Non-Condensing Tankless Water Heater has 8 other known error codes, including: 02 (Ignition Failure), 03 (Bath Fill Function Abnormality), 05 (Blocked Exhaust / Air Supply), 10 (Blocked Exhaust — Air Pressure Switch), 11 (No Ignition), and 3 more.

Error code 12 also appears on 8 other Rinnai models: Rinnai RL75iN RL Series Tankless Water Heater, Rinnai RL94iN RL Series Tankless Water Heater, Rinnai RSC160iN Condensing Combi Boiler, Rinnai RU130iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RU199iN Sensei Super High Efficiency Plus Tankless Water Heater, Rinnai RUR199iN Sensei Recirculating Tankless Water Heater, and 2 more. The fix may vary by model, so check each model's specific page for tailored repair steps.