BoilerFaultCodesThe 6 most common faults
01
Overheat indicator light High DIY-safe
Your boiler has detected that it got too hot or lost power, so it has automatically turned itself off to stay safe and needs to be reset.
What to try first
Turn the boiler settings dial to the 'Reset' position (or press the reset button if applicable).Wait for the boiler to cycle through its ignition sequence.If the light stays on, check if your heating system has enough water pressure or if a radiator valve is stuck closed.
02
Lockout High DIY-safe
Your boiler has automatically shut down to protect itself, likely because it got too hot or experienced a temporary glitch.
What to try first
Locate the main control knob on the front panel.Turn the knob to the OFF position and wait at least 10 seconds.Turn the knob back to the ON position to attempt a reset.
03
Lockout light on High DIY-safe
Your boiler has switched itself off because it got too hot, likely triggered by a safety cut-out to prevent damage.
What to try first
Turn the main control knob to the 'Off' position.Wait at least 10 seconds for the system to reset.Turn the control knob back on and check if the lockout light has cleared.
04
Overheat (Red LED) High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent damage.
Full guide for Overheat (Red LED)05
Overheat Neon High Engineer
Your boiler has automatically shut itself off because it reached a dangerously high temperature to prevent damage or safety hazards.
Full guide for Overheat Neon06
Overheat High Engineer
Your boiler has detected that it is running too hot and has automatically switched itself off as a safety precaution to prevent damage.
Full guide for Overheaton the Baxi Solo PF
Overheat thermostatPumpPrinted Circuit Board (PCB)Overheat ThermostatPCBSystem pump
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