Tankless Water Heater Error Codes — Complete List by Brand

Published: July 21, 2026 — CANRO Heating & Cooling — Greater Vancouver, BC

Navien Error Codes

Navien common codes: E001 — ignition failure (check gas supply, ignitor, flame rod). E003 — flame loss during operation (check condensate drain, venting). E110 — overheating (descaling needed). E301-303 — flow sensor issues (clean inlet filter). E416 — supply voltage issue (check electrical connection).

Rinnai Error Codes

Rinnai common codes: 11 — no ignition (check gas supply, ignition electrode). 12 — flame loss (check venting, condensate drain). 14 — overheating (clean heat exchanger). 51 — improper grounding (check electrical). 61 — water temperature sensor fault. 65 — flame rod short (replace flame rod).

Rheem and Bosch Codes

Rheem: ER — electronic control failure. LF — lockout due to excessive ignition attempts (reset by unplugging for 30 seconds). SL — scale buildup on heat exchanger (professional descaling needed). Bosch: A7 — ignition failure. A8 — flame failure. EA — temperature sensor fault. E9 — fan motor fault.

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Safety Reminder

If you smell gas, suspect carbon monoxide or believe there is an immediate danger, leave the property and contact emergency services or the appropriate gas emergency authority. Do not remain inside — exit the building immediately and call for help from outside.