37 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Replaced by: Greenstar i
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 has automatically turned itself off because the exhaust area is getting too hot, indicating a potential blockage or a problem with how the gases are clearing.
Your boiler has detected a critical internal error that caused it to shut down for safety reasons and will not restart on its own.
Your boiler has detected a critical internal error and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler's internal computer has developed a fault and can no longer safely control the heating or hot water functions.
Your boiler is currently stuck in a manual testing mode used by engineers and needs to be switched back to its normal operating setting.
Your boiler has detected a critical internal error and purposefully shut itself down to prevent damage, meaning you currently have no heating or hot water.
Your boiler is currently in a manual testing mode rather than a fault state, which is why it is temporarily limiting its output.
Your boiler is currently in a manual testing mode rather than a fault state, which is why it isn't heating your home normally.
Your boiler is currently in a manual testing mode set by the technician, which makes it run at its highest speed.
Your boiler has been accidentally switched into a specific testing mode used by engineers, rather than having a mechanical breakdown.
Your boiler has stopped working because it cannot confirm that the fan is blowing air through the flue correctly and safely.
Your boiler has detected that the exhaust gases are getting too hot and has shut down as a safety precaution to prevent damage.
Your boiler has shut down because it detected that the exhaust gases are getting too hot, which is a safety mechanism to prevent damage to the flue system.
Your boiler has detected that the water pressure is either too low or too high, or the gauge itself is reporting an incorrect reading.
Your boiler is struggling to pump water around your heating system, likely due to a blockage or a part that is stuck.
Your boiler is struggling to switch between heating your radiators and providing hot water because an internal motor or valve is stuck.
Your boiler is struggling to switch between heating your radiators and providing hot water, which means you may lose one or both of these functions.
Your boiler's internal temperature sensor has stopped sending the correct information to the main control board, preventing the system from heating up safely.
Your boiler has reached an unsafe temperature and has shut itself down to prevent damage.
Your boiler has detected that the water pressure has become too high and is releasing the excess through a safety valve.
Your boiler's internal pressure management system is failing, which is causing the system to shut down to prevent damage from pressure spikes.
Your boiler has lost water pressure, which is preventing it from firing up to provide heat or hot water.
Your boiler has detected an incorrect internal configuration chip that doesn't match the specific model's requirements.
Your boiler's internal computer chip has identified that it is configured for a specific model setup that doesn't match its current operation.
Your boiler has detected an incorrect or malfunctioning internal configuration plug, which prevents it from operating correctly.
Your boiler's internal computer chip is sending an incorrect or conflicting signal regarding how it manages hot water and heating.
Your boiler has detected an incorrect or missing internal configuration chip, which means the control system cannot communicate properly with the hardware.
Your boiler currently has no power, which means it cannot provide hot water or heating until the electrical connection is restored.
Your boiler is working perfectly, and the blue light simply indicates that it is currently powered on and ready to provide heating or hot water.
Your boiler's electronic brain is missing a crucial identification chip that tells it how to operate, so it has safely shut itself down until the part is properly installed.
Your boiler has completely lost power and is not showing any lights or signs of life.
Your boiler has been manually set to run at full power for testing purposes and just needs to be switched back to its normal operating mode.
Your boiler has lost all power and is completely unresponsive, meaning it is currently unable to provide any heating or hot water.
Your boiler is failing to switch on for heating even though your hot water is working perfectly fine.
Your boiler is receiving a signal to turn on even though your thermostat or timer is not asking for heating or hot water, which may keep the boiler running unnecessarily.
Your boiler has stopped responding to requests for heat or hot water and is stuck in a non-operational state.
Your boiler is heating the radiators normally, but it is failing to switch over to provide hot water to your taps.
BoilerFaultCodes