41 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
This boiler uses LED flash patterns
Count the flashes in one repeating group before the pause. That number is your fault code. Do not reset until you have noted it. How to read fault codes →
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Your boiler is struggling to burn fuel correctly because the balance of air is incorrect or a sensor is faulty.
Your boiler's safety sensor thinks there is a fire inside before it has even started, causing the system to shut down for safety.
Your boiler appears to have no power reaching the control panel, meaning the system is switched off or disconnected from the electricity supply.
Your boiler's burner has shut itself down for safety and needs to be restarted manually.
Your boiler's burner has stopped working because a small internal component is failing to give the motor enough power to start.
Your boiler is struggling to breathe properly, causing it to make a rhythmic thumping or vibrating sound as it burns fuel.
Your boiler is struggling to breathe properly, causing the flame to flicker irregularly and the unit to vibrate.
Your boiler has stopped working because its internal computer systems cannot communicate properly, preventing it from lighting the burner safely.
Your boiler is working fine but hasn't been told to turn on by your heating controls or timer.
Your boiler is struggling to heat your hot water correctly because of a communication issue between its sensors and the internal computer.
Your boiler's main internal computer has encountered a processing error and can no longer safely control the heating system.
Your boiler has detected too much pressure inside the system because the water isn't moving around properly or there is trapped air.
Your boiler has detected that there is not enough water in the system to operate safely, which has caused it to shut down.
Your boiler has stopped working because it cannot detect its outdoor temperature sensor, likely due to a wiring issue or a faulty component.
Your boiler has detected that the electrical wiring coming from your home’s power supply is connected the wrong way around.
Your boiler's internal computer parts are struggling to talk to each other, which prevents the system from starting up or running correctly.
Your boiler is not detecting water moving through the system, which is preventing it from firing up to provide hot water.
Your boiler is failing to reach the required temperature for heating your home, likely because of a setting issue or a buildup of soot inside the unit.
Your boiler has detected a general processing error or a mismatch in the ignition sequence that is preventing it from heating your home.
Your boiler has stopped working because the water pressure in your radiators has dropped too low.
Your boiler has no power arriving at the unit, meaning it cannot start the burner to provide heating or hot water.
Your boiler has lost power because an internal electrical component has failed, meaning the screen is blank and the heating will not turn on.
Your boiler is unable to pull oil from the tank to create a flame, likely because the fuel is low or a valve is closed.
Your boiler's burner has detected light when it should be dark inside, causing it to shut down for safety.
You can smell heating oil near your boiler, which usually indicates a fuel leak that needs urgent attention to prevent damage or fire risk.
You have likely developed a leak in your fuel delivery system or burner which is causing a strong smell of heating oil in or around your home.
Your boiler has lost connection with a temperature sensor and has shut down as a safety precaution.
Your boiler is struggling to work out the weather outside because the external temperature sensor has lost its connection or stopped working.
Your boiler has lost electrical power and cannot operate, which is usually caused by a switched-off breaker or a simple blown fuse.
Your boiler has lost electrical power and cannot start or run any of its functions.
Your boiler has stopped working because it cannot correctly measure the temperature of the water returning from your radiators.
Your boiler has detected a problem with the sensor that monitors the temperature of the exhaust gases, and it has likely shut down for safety.
Your boiler's internal thermometer has stopped working correctly, meaning the system can no longer safely monitor its own temperature to provide heating.
Your boiler has stopped working because it cannot correctly monitor the temperature of the gases leaving the system.
Your boiler has stopped working because its internal thermometer, which checks the temperature of the air around it, has developed a fault.
Your boiler has sensed that the internal exhaust gases have become too hot and has shut down as a safety precaution.
Your boiler has detected very cold temperatures and has automatically turned on its built-in safety mode to prevent the internal pipes from freezing.
Your boiler has stopped working because it cannot detect a flame or is struggling to ignite the fuel properly.
Your boiler has detected an electrical fault with its temperature sensors, which means it cannot accurately measure the water flow and has stopped working for safety.
Your boiler's internal thermometer that monitors water temperature is broken or has a loose connection, preventing the system from heating up safely.
Your boiler's electronic control system has encountered a communication error or internal memory fault, likely requiring a professional software reset or control board inspection.
BoilerFaultCodes