BoilerFaultCodesThe 6 most common faults
Your boiler is unable to light the flame needed to heat your water and home.
Why it happens: This fault occurs when the boiler attempts to start up but cannot successfully establish or detect a flame. The most common reasons include a lack of gas reaching the unit, a worn-out ignition spark, or a build-up of carbon on the internal sensors that tell the boiler it is safe to keep running.
Check if other gas appliances, like a hob, are working to confirm gas supplyEnsure your prepaid gas meter (if applicable) has creditRotate the mode selector switch to the 'Reset' position for a few seconds, then back to its original setting
Your boiler has shut down because it has detected it is getting too hot, triggering a safety switch to prevent damage.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature, causing the safety limit thermostat to trip and shut everything down. The most common reasons are a pump failure preventing water from circulating or a buildup of limescale and sludge blocking the internal heat exchanger. It can also happen if there is trapped air in the system or if all your radiator valves are closed at once.
Check that your radiator valves are open to allow water to flow.Ensure your system pressure is between 1.0 and 1.5 bar on the pressure gauge.Wait for the boiler to cool down and try turning the mode selector switch to 'Reset'.
Your boiler has stopped working because the water pressure inside the system has dropped too low to operate safely.
Why it happens: This fault occurs when the internal water pressure drops below the minimum level required for the boiler to fire up safely. The most common reasons are a slow leak hidden somewhere in your pipework or radiators, or because you recently bled your radiators without topping the system back up.
Locate the filling loop (usually a silver flexible hose) underneath or near the boiler.Open the small valves on the filling loop slowly until you hear water entering the system.Watch the pressure gauge and close the valves tightly once the needle reaches 1.5 bar.
Your boiler has shut down because a sensor detected that the water inside has become far too hot.
Why it happens: This fault occurs when the water within the boiler's main heat exchanger reaches an unsafe temperature, triggering a safety shutdown to prevent damage. The most common reasons are a pump failure preventing water from moving around the system or a build-up of sludge and debris that blocks the flow.
Turn the boiler off at the electrical switch or dial.Ensure all radiator valves are fully open to allow heat to dissipate.Wait 20 minutes for the system to cool, then turn the boiler back on and rotate the mode selector to the 'reset' position.
Your boiler has detected an issue with how it is getting rid of exhaust fumes, which has caused it to shut down for safety.
Why it happens: This fault occurs when the boiler's safety sensors detect that the fan isn't moving air effectively or that exhaust gases are not being safely cleared through the flue pipe. The most common reason is a blockage in the small plastic tubes inside the boiler, a failing fan motor, or debris obstructing the air passage from outside.
Full guide for 03Your boiler's temperature sensor for the central heating system has failed or developed a fault, meaning the boiler cannot accurately gauge how hot the water is.
Why it happens: This fault occurs when the internal sensor responsible for tracking the temperature of your radiators fails to send a reliable signal to the main control board. The most common reason is that the sensor's internal electrical resistance has drifted out of range due to age or heat degradation, though loose or corroded wiring can also trigger the alert.
Full guide for 05on the Vokera Linea 24
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