BoilerFaultCodesThe 4 most common faults
Your boiler has completely lost power and its display screen is blank, meaning it cannot operate or heat your home.
Why it happens: This fault occurs when the boiler's electrical circuit is broken, preventing power from reaching the internal computer. The most common reasons are a tripped fuse in your home's consumer unit, a blown fuse inside the boiler itself, or a total failure of the main printed circuit board. Essentially, the boiler is unable to 'wake up' because its electrical supply has been cut off.
Check if other appliances are working to rule out a general power cutCheck your home's main consumer unit (fuse box) to see if a circuit has trippedCheck the fused spur switch next to the boiler is turned on and the fuse inside hasn't blown
Your boiler is providing hot water as normal, but there is a communication issue preventing the heating from turning on when you use your thermostat.
Why it happens: This issue occurs when the link between your heating controls and the boiler is broken, meaning the boiler doesn't 'hear' the signal to turn on. The most common reason is a pair of flat batteries in your wall thermostat or a technical failure in the wireless receiver box attached to the boiler.
Check that the batteries in your wall thermostat or room programmer haven't run outEnsure the heating timer is set to 'ON' or 'AUTO' and the thermostat is turned up higher than the current room temperatureCheck if any wireless receiver attached to the boiler has a power light or is showing a signal connection
Your boiler has failed to light the flame after several attempts and has safely shut itself down to prevent a gas buildup.
Full guide for LOCKOUTYour boiler is signalling a general internal fault that has caused it to stop working to ensure your safety.
Full guide for Blue indicator light flashingon the Worcester Bosch 28i RSF
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 Worcester Bosch 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