BoilerFaultCodes
The most common Zanussi faults
Your boiler has shut down because the water inside it has become too hot, usually due to a lack of circulation or a blockage in the system.
Why it happens: This fault occurs when the internal sensors detect that the water is heating up too quickly or has reached a dangerously high temperature. The most common reason is that the water cannot move through the boiler properly, which is often caused by a failed pump, a blockage of sludge in the system, or air trapped within the unit.
Check that your radiator valves are fully open.Ensure the boiler pressure is between 1 and 1.5 bar on the gauge.Reset the boiler by turning the control knob to 'Reset' and then back to 'On'.
Your boiler has stopped working because it cannot light a flame, which is often caused by a lack of gas supply or a blocked pipe.
Why it happens: This fault occurs when the boiler tries to light itself several times but fails to detect a flame, causing the system to shut down for safety. The most common reasons are a lack of gas reaching the unit, a blocked pipe that carries away waste water, or a dirty internal component that can no longer create a spark. It can also happen after a temporary disruption to your local gas supply or if the meter has run out of credit.
Check if your gas meter has credit and that the gas emergency control valve is open.If it is freezing outside, check if your white condensate pipe is frozen and thaw it with warm water.Press the 'Restart' button on the boiler display to try again.
Your boiler has detected that the water pressure inside the system is too low to run safely and has stopped working as a result.
Why it happens: This fault occurs when the internal water pressure drops below the minimum level required for the boiler to operate safely. The most common reasons are a slow leak from a radiator valve or pipework, or a loss of air pressure in the expansion vessel which helps regulate the water volume.
Locate the filling loop (usually a silver flexible hose with one or two blue handles underneath the boiler).Slowly open the valve or valves until you hear water flowing and watch the pressure gauge.Close the valves tightly once the pressure gauge reaches between 1.0 and 1.5 bar.
Your boiler is failing to stay lit or cannot detect its own flame, meaning it has shut down for safety and will not provide heating or hot water.
Why it happens: This fault occurs when the boiler's control system can no longer detect the flame required to heat your water, causing it to shut down for safety. The most common reasons include a buildup of carbon on the sensing probe, a skip in the gas supply, or an internal component failing to provide a consistent spark.
Check if other gas appliances, like a hob, are working to ensure gas supply is activeIf it is freezing outside, check if the white plastic condensate pipe leading outdoors is frozen and thaw it with warm waterPress the 'Restart' button on the front control panel to reset the boiler
Your boiler has lit correctly but the flame has gone out unexpectedly, often due to a temporary interruption in the gas supply or a blocked condensate pipe.
Why it happens: This fault happens when the boiler successfully starts up, but the flame goes out shortly after because the system can no longer detect it. The most common reasons are a lack of gas entering the unit, a dirty sensor that can't 'see' the flame, or a blockage in the pipe that carries away waste liquid.
Check that your gas meter has credit and the isolation valve is open.Inspect the white plastic pipe (condensate) leading outside for signs of freezing or blockages.Restart the boiler by pressing the 'Reset' button.
Your boiler is struggling to keep its flame lit, which means it cannot heat your water or radiators reliably.
Why it happens: This fault occurs when the boiler's internal sensor can no longer detect a steady flame after the burner has ignited. The most common reasons are a worn-out sensing probe that can't 'see' the fire, or an unstable gas supply that causes the flame to drift and extinguish prematurely.
Check that your gas emergency control valve is open and you have credit on your gas meter.Check if other gas appliances in your home, like a hob, are working correctly.Reset the boiler by turning the mode knob to 'RE' and then back to your desired setting.During freezing weather, check that the white plastic condensate pipe leading outside is not frozen.
Your boiler has started an ignition process but the flame has gone out, meaning the system has shut down for safety.
Why it happens: This fault occurs when the boiler successfully lights but the internal sensors fail to detect the flame, causing the system to shut down for safety. The most common reasons are worn-out ignition parts that can no longer 'see' the fire, or an inconsistent gas supply that prevents the flame from staying lit. In some cases, a blocked flue or debris on the burner can also interfere with the combustion process.
Check that your gas stop tap is fully open and that you have credit on your gas meter.Check if other gas appliances in your home, such as a hob, are working correctly.Reset the boiler by turning the primary knob to the 'RESET' position and holding for five seconds.
Your boiler has detected that the water is heating up too quickly or isn't moving through the system properly, causing it to overheat and shut down for safety.
Why it happens: This fault happens when heat cannot escape the boiler quickly enough, causing the internal temperature to spike dangerously fast. It is usually caused by a pump failure that stops water from moving or a blockage in the pipes, such as a buildup of sludge or closed valves, that prevents circulation. Effectively, the boiler is producing heat but has nowhere to send it, so it shuts down to prevent damage.
Check that at least two or three radiator valves are fully open to allow water flow.Ensure the large blue and red isolation valves underneath the boiler are in the 'open' position.Try resetting the boiler by turning the control knob to 'Reset' and then back to the original setting.
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