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 a flame when it shouldn't be there, but it has already cleared the error itself and should be safe to continue running.

Your boiler’s internal computer is struggling to identify its own configuration settings, which prevents it from starting up correctly.

Your boiler's control panel has lost its connection to the main computer, meaning the system cannot receive commands or display information correctly.

Your boiler has detected that it is running out of water inside its internal system, which prevents it from heating your home safely.

Your boiler has detected an issue related to the flow of water or heat exchange, often caused by a buildup of debris or a sensor struggling to track the water movement.

Your boiler has detected that it is not receiving any gas, or it is failing to ignite properly.

Your boiler has detected an issue with the water pressure level, which is causing it to stop operating to prevent damage.

Your boiler has detected an issue with the air flow or exhaust system, causing it to shut down to remain safe.

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 an issue with the airflow system, which means it has safely shut itself down to prevent it from operating incorrectly.

Your boiler has detected an issue with the air flowing through the system, meaning it cannot operate safely and has shut down.

Your boiler has detected a problem with the flow of water or an issue with the pump, meaning it has safely shut down to prevent damage.

Your boiler has detected an internal communication failure between its main control boards, which prevents it from operating correctly.

Your boiler has detected a communication error between its internal parts, meaning it has safely shut down to prevent incorrect operation.

Your boiler has detected an issue with the internal air or exhaust system that is preventing it from operating safely.

Your boiler is having difficulty communicating with its internal control system, which has caused it to stop working to avoid potential damage.

Your boiler has detected an issue with the water flow or circulation sensor, which is preventing it from heating your home or water correctly.

Your boiler has detected a communication error between its main computer and the internal circuit board, which effectively shuts down the system to prevent incorrect operation.

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 failed to light the flame needed to produce heat or hot water, and it has safely locked itself to prevent gas flow.

Your boiler has stopped working because the water pressure inside the system is too low to run safely.

Your boiler has stopped working because the water pressure inside the heating system has dropped below the required level.

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

Your boiler has detected that it is running at a temperature higher than it should be and has switched itself off to prevent internal damage.

Your boiler is trying to start but cannot get the flame going, which means you currently have no heating or hot water.

Your boiler has detected that the gases leaving through your flue are too hot, suggesting the system is overheating and has shut itself down to prevent damage.

Your boiler has lost its flame while trying to heat your water or home, causing it to shut down to stay safe.

Your boiler is trying to start up but is failing to light the flame, so it has safely stopped trying to prevent a gas build-up.

Your boiler is failing to detect the flow of water needed to provide hot water or heating, likely because a sensor is stuck or faulty.

Your boiler's main control computer is experiencing an internal electronic fault and is unable to operate correctly.

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 has detected that a temperature sensor is not working correctly, so it has safely shut down to prevent potential damage.

Your boiler has detected that the temperature of the gases leaving the flue is higher than it should be, so it has safely shut itself down to prevent damage.

Your boiler is struggling to clear exhaust gases safely, so it has stopped working to prevent any risk to your home.

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 an issue with the sensor that monitors the temperature of the gases leaving your flue, meaning the boiler has stopped working to prevent overheating.

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 stopped heating your radiators because a sensor is failing to correctly read the water temperature.

Your boiler is struggling to accurately measure the water pressure inside the system, which is preventing it from running safely.

Your boiler's computer is confused because its internal configuration settings have been reset or were never correctly programmed at installation.

Your boiler's electronic control board and the display screen are failing to talk to each other, which means the system cannot receive commands or function properly.

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's air extraction system has stopped working, meaning the unit cannot safely vent exhaust gases and will shut down to prevent a hazard.

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 monitor the water pressure in your heating system, so it has safely shut down to prevent potential damage.

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

Your boiler has detected that water is leaking internally or not heating up as expected within its hot water system.

Your boiler is struggling to accurately measure the temperature of the water circulating through your radiators, so it has safely shut itself down to prevent potential overheating.

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 detect when you turn on the hot tap, meaning it isn't heating water for your taps or shower as it should.

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 currently unable to tell if water is moving through the system, so it has safely shut down to prevent damage.

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 control panel has lost its connection to the main computer, meaning the system cannot communicate or respond to your settings.

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 is struggling to accurately measure the water flow or pressure inside the system, which is preventing it from heating your home safely.

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.

Your boiler is failing to light the fuel safely and has shut itself down to prevent a gas buildup.