BoilerFaultCodesThe 6 most common faults
Your boiler is failing to light the gas or cannot stay lit, meaning you currently have no heating or hot water.
Why it happens: This fault occurs when the boiler tries to start but fails to detect a steady flame after several attempts. It is usually caused by a dirty ignition probe that cannot spark correctly, a lack of gas reaching the burner, or a faulty sensor that fails to tell the boiler that the flame is actually lit.
Check if other gas appliances, like a hob, are working to ensure gas is being supplied to the home.Ensure your gas meter has credit if you are on a pre-payment meter.Press the 'Reset' button on the front of the boiler once to see if the system restarts.
Your boiler has sensed it is getting too hot and has automatically shut down to prevent damage or safety issues.
Why it happens: This fault occurs when the water inside the heat exchanger reaches an unsafe temperature, triggering a safety switch to cut the power. The most common reasons are a pump failure preventing water from circulating or a build-up of sludge and debris that blocks the flow of heat away from the burner.
Check that all radiator valves are fully open to allow water to circulate.Ensure there is enough pressure in the system by checking the gauge is between 1 and 1.5 bar.Gently press the 'Reset' button on the control panel once the boiler has cooled down.
Your boiler has built up too much internal water pressure and is releasing it through a safety valve to prevent damage.
Why it happens: This fault occurs when the water pressure inside your heating system rises above safe levels, often because the expansion vessel has lost its air charge or failed. The boiler triggers this code as it uses a safety valve to eject water and protect internal components from being crushed by the high pressure. It can also happen if the filling loop was left slightly open, causing the system to overfill unintentionally.
Check that the filling loop valves are fully closed and not letting in more waterBleed water from a radiator to reduce the system pressure to between 1.0 and 1.5 barCheck the external copper discharge pipe for signs of drippingIf the pressure continues to rise or the valve leaks, call a Gas Safe engineer
Your boiler has detected that the water pressure inside the system is too low and has switched itself off as a safety precaution.
Why it happens: This fault occurs when the water level inside your central heating system drops below a safe threshold, leaving the boiler unable to circulate heat. The most common reasons are a slow leak from a radiator valve or pipework, or the air being let out of the system during recent maintenance or bleeding of radiators.
Locate the filling loop (the flexible silver hose) underneath or near the boilerSlowly open the one or two taps/valves until you hear water enteringWatch the pressure gauge until it reaches between 1 and 1.5 bar, then close the valves tightly
Your boiler has failed to light the gas burner, which means you will not have any heating or hot water at the moment.
Why it happens: This fault occurs when the boiler tries to light the gas three times but fails to detect a flame. The most common reasons are a disruption to your gas supply, a worn-out ignition spark, or a component failure that prevents the gas from flowing correctly into the burner.
Check if other gas appliances, like a cooker, are working to ensure gas is reaching the property.Press the 'Reset' button and hold it for a few seconds to try and restart the ignition sequence.Verify that your gas meter has credit if you use a pre-payment meter.
Your boiler has sensed it is getting too hot, usually because the water inside isn't moving around the system correctly.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature, triggering a safety sensor to shut the system down. The most common reason is that the water is unable to move through the pipes quickly enough to carry heat away, often due to a broken pump or a blockage in the system. It can also be caused by a build-up of limescale or debris within the heat exchanger that prevents efficient heat transfer.
Check that your radiator valves and the boiler isolation valves are fully openEnsure your system water pressure is between 1 and 1.5 bar on the pressure gaugeWait for the boiler to cool down completely, then turn the control knob to the 'Reset' position for a few seconds
on the Vokera Linea Max
Based on parts cited in our fault code database. Your engineer will confirm what's actually needed after diagnosis.
Call a Gas Safe engineer if…
- You can smell gas or see signs of a leak
- The Vokera shows an Emergency or High severity code
- The boiler keeps locking out after repeated resets
- You've tried the DIY checks and the fault hasn't cleared
- There's visible water leaking from the boiler
- The flame is yellow or orange instead of blue