BoilerFaultCodesThe 6 most common faults
Your boiler is trying to start up but cannot light the gas or detect a flame, causing the system to shut down for safety.
Check if other gas appliances, like a hob, are working to confirm gas supply.Ensure your gas meter has credit if you use a prepay system.Press the 'Reset' button on the front of the boiler control panel.
Your boiler has switched itself off for safety because it has become too hot inside, likely due to a circulation blockage or a pump failure.
Ensure all radiator valves (TRVs) are turned to their highest setting to allow water to flow.Check that the boiler pressure is between 1 and 1.5 bar on the gauge.Press and hold the 'R' reset button for several seconds to restart the boiler.
Your boiler has been manually reset too many times in a short period and has now locked itself out for safety.
Turn the boiler power off at the fused spur switch (the wall switch near the boiler).Wait for at least 30 seconds.Turn the power back on to clear the temporary lockout memory.
Your boiler has detected that the water pressure in the central heating system is too low to run safely.
Locate the filling loop (usually a silver flexible hose) underneath or near the boilerSlowly open the valve(s) to let water into the system while watching the pressure gaugeClose the valves firmly once the needle reaches between 1.0 and 1.5 bar
Your boiler has detected air trapped inside the pump, which is preventing water from circulating correctly and causing the system to stop working.
Check your boiler's pressure gauge and top it up to 1.5 bar if it is below 1.0 bar.Locate the manual air bleed screw on the center of the pump if accessible.Carefully loosen the screw slightly to let trapped air escape until water drips out, then tighten it back securely.
Your boiler has shut down because the exhaust gases have become too hot, which is a safety measure to prevent damage to the flue and internal components.
Full guide for 03on the Alpha E-Tec Plus NX
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 Alpha 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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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