BoilerFaultCodesThe 3 most common faults
01
Lockout High DIY-safe
Your boiler has safely shut itself down because it failed to ignite properly.
What to try first
Check that your gas supply is working by testing another gas appliance like a hob.Locate the reset button on your Baxi Suprima, press it firmly, and hold it for about 5 seconds.Wait to see if the boiler fires up normally; do not repeat this more than twice if it fails again.
02
Blocking - Mains Frequency incorrect or Air Switch Fault High Engineer
Your boiler has stopped working because it has detected an issue with the air pressure or the electrical supply, which usually happens when a safety switch gets stuck.
Full guide for Blocking - Mains Frequency incorrect or Air Switch Fault03
Earth Fault or Mains Reversal Emergency Engineer
Your boiler has detected an electrical safety issue with its wiring or power supply.
Full guide for Earth Fault or Mains Reversalon the Baxi Suprima 30
PCBIgnition leadGas valveAir pressure switchPressure switch tubingPrinted Circuit Board (PCB)
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 Baxi 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