Navien NCB Fault codes & diagnostics

Your boiler has failed to ignite the flame correctly after several attempts and has stopped working to prevent a buildup of gas.

Your boiler has detected a failure to ignite or a loss of flame, meaning it cannot start the heating process successfully.

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

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

Your boiler is failing to light the flame properly, so it has stopped trying to prevent gas from building up inside.

Your boiler has stopped because the flame inside has gone out and will not stay lit, meaning you currently have no heating or hot water.

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

Your boiler is overheating because it cannot effectively transfer heat to your water, likely due to a build-up of internal mineral deposits.

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

Your boiler has detected that the temperature in the exhaust flue is too high, so it has safely shut itself down to prevent damage.

Your boiler has detected an issue with the air-to-gas ratio system, meaning it cannot safely control the combustion process and has shut down to protect your home.

Your boiler has stopped working because the mechanical fan that pushes waste gases outside is not spinning as it should.

Your boiler has detected a blockage in the drainage pipe that removes waste water, which is preventing it from running safely.

Your boiler is having difficulty detecting the necessary airflow required to operate safely and has shut down to prevent any risk.

Your boiler is struggling to accurately measure the temperature of the water circulating through your radiators, so it has stopped heating to prevent potential damage.

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

Your boiler has detected that the hot water flow and the cooler return water are being identified in the wrong order, likely due to a sensor misreading or a plumbing configuration issue.

Your boiler has switched off because the internal water pressure has dropped too low to operate safely.

Your boiler is struggling to accurately read the water pressure in your system, which prevents it from operating safely.

Your boiler is having trouble detecting how much water is inside the system, which prevents it from firing up safely.

Your boiler is struggling to accurately measure the temperature of the hot water leaving the unit because a sensor has stopped communicating correctly.

Your boiler is having trouble measuring the temperature of the water being sent to your radiators, so it has safely shut down to prevent overheating.

Your boiler is struggling to accurately measure or regulate the flow of water inside the system, which is causing it to stop heating as a safety precaution.

Your boiler is struggling to detect the temperature of your hot water, so it has safely shut down to prevent incorrect water temperatures.

Your boiler is having trouble controlling the temperature of the water being sent to your taps or radiators because a internal valve is not moving correctly.

Your boiler is struggling to detect the temperature of your hot water supply because a connection to one of its sensors has been lost.

Your boiler's electronic brain is detecting an internal communication error and has safely shut down to prevent incorrect operation.

Your boiler has detected an incorrect configuration setting on its internal computer, which is preventing it from starting up correctly.

Your boiler's computer memory is experiencing a fault, meaning it has lost its settings or cannot communicate with its internal control system correctly.

Your boiler's internal computer is experiencing a system error and cannot process commands correctly, meaning it will likely stop working to protect itself.

Your boiler's main control system is having difficulty communicating with its display panel, which has caused the unit to stop functioning.

Your boiler has lost its connection to the digital wall thermostat or controller it uses to talk to the rest of your heating system.

Your boiler has detected that its internal settings do not match the type of gas being supplied to your home, preventing it from firing up safely.

Your boiler is trying to start but cannot light the flame, which means it has safely shut itself down to prevent a gas buildup.