BoilerFaultCodesThe 4 most common faults
01
Lights Flash Off Flash High DIY-safe
Your boiler is not receiving enough electrical power from the main supply to operate safely.
What to try first
Check if other appliances in your home are flickering or behaving strangelyCheck your fuse box (consumer unit) for any tripped switchesContact your electricity provider to see if there is a known power fluctuations issue in your area
02
Lights Flash Off On High DIY-safe
Your boiler has got too hot and has shut itself down for safety, which is why your heating and hot water have stopped working.
What to try first
Turn the boiler power off at the wall socket or fused spurAllow the boiler to cool down for at least 30 minutesPress the 'Reset' button (located at the bottom of the boiler) or turn the control knob to the 'R' position and back to 'On'
03
Lights Flash Flash On High Engineer
Your boiler has stopped working because the internal fan, which safely clears waste gases, is unable to start or spin correctly.
Full guide for Lights Flash Flash On04
Lights On Off Flash Emergency Engineer
Your boiler has detected that the electrical wiring coming into the unit is connected backwards, which is a safety risk and prevents the system from starting.
Full guide for Lights On Off Flashon the Baxi Solo 3
External fusePrinted Circuit Board (PCB)Overheat ThermostatFlow ThermostatCirculation PumpFan Assembly
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