BoilerFaultCodesThe 6 most common faults
01
26 High DIY-safe
Your boiler has stopped working because the water pressure inside the heating system has dropped too low.
What to try first
Locate the external filling loop, usually a small silver braided hose with one or two valves underneath the boiler.Open the valve(s) slowly to allow water into the system until the pressure gauge reads between 1.0 and 1.5 bar.Close the valve(s) firmly and ensure no water is leaking from the connection.
02
02 High Engineer
Your boiler is trying to light but cannot successfully ignite the flame to start heating your home.
Full guide for 0203
05 High Engineer
Your boiler has detected an internal computer error that is preventing it from running safely.
Full guide for 0504
06 High Engineer
Your boiler has detected an internal computer error that is preventing it from starting up correctly.
Full guide for 0605
13 High Engineer
Your boiler's main control computer is experiencing an internal error, meaning the system has stopped working to prevent further damage.
Full guide for 1306
14 High Engineer
Your boiler has detected an internal electronic error within its main control system that is preventing it from operating safely.
Full guide for 14on the Alpha SY9 24
Pressure relief valvePressure gaugeExpansion vesselIgnition electrodeGas valvePCB
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