BoilerFaultCodesThe 3 most common faults
01
Faulty fan High Engineer
Your boiler's air circulation system has stopped working because the mechanical unit that pushes air through the vents isn't receiving the correct power to start up.
Full guide for Faulty fan02
Faulty PCB High Engineer
Your boiler's electronic brain is unable to send the correct signals to the fan, which prevents the system from starting up safely.
Full guide for Faulty PCB03
Faulty sensor Medium Engineer
Your boiler's control panel has lost communication with a temperature sensor, which is preventing it from heating your home correctly.
Full guide for Faulty sensoron the Johnson Starley Aquair S 10
Fan assemblyControl PCBPrinted Circuit Board (PCB)Wiring HarnessTemperature sensorWiring harness
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 Johnson Starley 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