Navien NCB H Fault codes & diagnostics

Your boiler has detected an internal communication error and has safely shut itself down as a precaution.

Your boiler has failed to light the flame properly and has stopped attempting to heat your home or water for safety reasons.

Your boiler has detected a false flame signal, meaning the system thinks the burner is lit when it should be turned off.

Your boiler has detected that it is not receiving enough water flow to operate safely or effectively.

Your boiler has detected an issue related to the flow of water inside the unit, which has caused it to stop working to protect itself from potential overheating.

Your boiler has failed to ignite or has lost the flame during operation because it is not receiving a consistent supply of gas.

Your boiler has detected an issue with the sensors that monitor the water flow, which is preventing it from firing up correctly.

Your boiler has detected a problem with the internal fan that controls the airflow needed to operate safely.

Your boiler has detected an issue with the air supply or exhaust system, meaning it cannot operate safely and has shut down to prevent damage.

Your boiler has detected an issue with the airflow or exhaust system, meaning it cannot operate safely and has shut itself down.

Your boiler has detected an issue with the air flowing through the flue system, causing it to shut down for safety.

Your boiler has detected an issue with the water pressure sensor, preventing it from knowing if there is enough water to safely heat your home.

Your boiler has detected an issue with the air flowing through the system, preventing it from starting safely.

Your boiler is experiencing a communication failure between the control panel and the main operating system preventing it from firing up correctly.

Your boiler has detected an issue with the air supply or exhaust ventilation system that prevents it from firing safely.

Your boiler has detected an issue with the sensor that tracks the flow of water, which is preventing the system from operating correctly.

Your boiler's fan is failing to run correctly, which prevents it from safely venting gases, so the system has shut down to protect your home.

Your boiler has detected an internal communication or software management error that requires a professional to reset or update its internal settings.

Your boiler's main control unit and the display panel are having trouble 'talking' to each other, which prevents the system from operating correctly.

Your boiler has detected that the water temperature inside is getting dangerously high and has shut itself down to prevent damage or overheating.

Your boiler has failed to light the flame needed to heat your water and home.

Your boiler has detected a flame when it shouldn't be burning, suggesting a sensor error or a gas valve issue that prevents the unit from starting safely.

Your boiler is failing to stay lit, so it has shut down to keep you safe.

Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent any damage to its internal parts.

Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.

Your boiler is having trouble managing the air and gas mixture needed to burn fuel safely and effectively.

Your boiler's fan is struggling to spin correctly, which prevents it from safely venting gases and means the boiler has shut down to keep you safe.

Your boiler is having trouble breathing, which prevents it from safely venting exhaust gases and starting your heating.

Your boiler's air pressure sensor is failing to communicate properly, which means the safety system is preventing the burner from lighting to ensure the unit operates safely.

Your boiler has lost the ability to accurately measure the temperature of the water being sent to your radiators, so it has safely shut itself down to prevent overheating.

Your boiler has lost the ability to read the temperature of the water returning to it, so it has shut down as a precaution to prevent overheating.

Your boiler has stopped working because the water pressure inside the heating system has dropped too low.

Your boiler has been trying to refill its internal water supply for too long but has failed to reach the required level.

Your boiler has detected that the water pressure inside the heating system is too high for it to operate safely.

Your boiler is struggling to accurately read the water pressure inside the system, which is preventing it from firing up safely.

Your boiler is struggling to detect the temperature of the water for your taps and shower because a sensor has stopped communicating correctly.

Your boiler is having trouble measuring incoming water temperature due to a faulty sensor, which is currently preventing it from heating your water correctly.

Your boiler is struggling to detect the flow of water through the system, which means it cannot safely heat your home or provide hot water.

Your boiler's main computer is having trouble processing information and needs to be looked at by a professional.

Your boiler's internal configuration settings are currently mismatched, which is preventing it from starting up correctly.

Your boiler's computer memory has encountered a data error, which is preventing it from starting up correctly.

Your boiler's computer has detected an internal error with its data storage, meaning it cannot reliably operate its settings or programs.

Your boiler's main control panel is failing to communicate with the internal system, which will prevent your heating and hot water from working properly.

Your boiler is having trouble communicating with your wall-mounted thermostat or smart control system, which prevents it from knowing when to turn on your heating.

Your boiler is failing to light the internal flame, which means it cannot produce any hot water or heating for your home.

Your boiler is struggling to light its internal flame, which means it has automatically shut down to prevent gas from building up.