BoilerFaultCodesThe 6 most common faults
01
10 High DIY-safe
Your boiler has stopped working because the water pressure inside your heating system has dropped too low.
What to try first
Locate the external filling loop, usually a silver braided hose near the boiler pipes.Open the valves on both ends of the filling loop to allow water into the system.Watch the pressure gauge on the front of the boiler until it reaches the green zone (usually 1.0 to 1.5 bar).Close both valves firmly and ensure the filling loop is disconnected if required.
02
27 High DIY-safe
Your boiler is struggling to circulate water properly around your heating system, which usually means the system pressure is too low or there is a blockage.
What to try first
Check your boiler's pressure gauge and ensure it is between 1.0 and 1.5 barIf the pressure is low, use the filling loop to top up the system to the correct pressureEnsure all radiator valves are fully open to allow water to circulate freely
03
01 High Engineer
Your boiler is failing to light the burner, meaning it cannot produce heat or hot water because it does not detect a flame.
Full guide for 0104
02 High Engineer
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent damage.
Full guide for 0205
03 High Engineer
Your boiler has detected that the exhaust gases leaving your home are becoming dangerously hot and has shut itself down to prevent overheating.
Full guide for 0306
04 High Engineer
Your boiler has detected a communication error with its gas supply component, meaning it cannot safely ignite to provide heating or hot water.
Full guide for 04on the Alpha Intec S
Pressure gaugeFilling loopPressure sensorCirculation pumpDiverter valveIgnition electrode
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