Boiler Error Codes & Troubleshooting
Look up error codes from top boiler brands. Understand what they mean and when to call an emergency technician.
Air Supply/Exhaust Blockage (Navien)
Navien boiler detected a blockage in the air supply or exhaust venting system and shut down.
Ignition Failure (Navien)
Navien boiler failed to ignite the burner after multiple attempts and locked out.
Overheating (Navien)
Navien boiler water temperature exceeded the maximum safety limit, triggering emergency shutdown.
Flow Sensor Issue (Navien)
Navien boiler flow sensor is not detecting sufficient water flow for safe operation.
Boiler Shutdown - No Flame (Viessmann)
Viessmann boiler detected flame failure during operation and shut down the burner.
Outdoor Temperature Sensor Fault (Viessmann)
Viessmann boiler outdoor temperature sensor has failed or is providing an incorrect reading.
DHW Sensor Fault (Viessmann)
Viessmann boiler domestic hot water temperature sensor is reading outside normal range.
Blocked Vent (Weil-McLain)
Weil-McLain boiler vent blockage detected, shutting down the system for safety.
Ignition Lockout (Weil-McLain)
Weil-McLain boiler has locked out after repeated ignition failures.
Low Water Pressure (Weil-McLain)
Weil-McLain boiler system water pressure is too low for safe operation.
NTC Thermistor Error (Navien)
Navien boiler temperature sensor (NTC thermistor) is reading outside the valid range.
Water Pressure Sensor Error (Navien)
Navien boiler water pressure sensor is reading outside the normal operating range.
Gas Valve Failure (Navien)
Navien boiler detected a gas valve electrical fault and shut down the system.
Combustion Fan Error (Navien)
Navien boiler combustion fan is not operating at the correct speed or has failed.
Flow Switch Error (Navien)
Navien boiler flow switch is stuck open or not detecting water flow during DHW demand.
PCB Communication Error (Navien)
Navien boiler control board communication error between main and display PCBs.
Gas Pressure Switch Error (Viessmann)
Viessmann boiler gas pressure switch indicates insufficient or excessive gas pressure.
Flue Gas Temperature Too High (Viessmann)
Viessmann boiler flue gas temperature has exceeded the maximum safe limit.
Freeze Protection Active (Navien)
Navien boiler antifreeze function has activated due to low water temperature risk.
Heat Exchanger Overheat Protection (Buderus)
Buderus boiler heat exchanger temperature exceeded the safety limit, triggering shutdown.
Burner Failure (Buderus)
Buderus boiler burner failed to ignite or lost flame during operation.
Boiler NTC Sensor Failure (Lochinvar)
Lochinvar boiler temperature sensor has failed open or short circuit.
Low Water Cutoff Error (Lochinvar)
Lochinvar boiler low water cutoff sensor has detected insufficient water level.