BoilerFaultCodesThe 6 most common faults
01
212 High Engineer
Your boiler is shutting down because it is heating up much faster than it can circulate the water, which often points to a blockage or a pump issue.
Full guide for 21202
214 High Engineer
Your boiler has stopped working because the internal component responsible for clearing exhaust gases is not spinning, preventing the burner from safely igniting.
Full guide for 21403
215 High Engineer
Your boiler has detected that its internal air fan is spinning much faster than it should be, causing the system to stop working to ensure safety.
Full guide for 21504
224 High Engineer
Your boiler has detected that it is running too hot and has automatically shut itself down to prevent any damage or safety issues.
Full guide for 22405
227 High Engineer
Your boiler is trying to start, but it cannot detect a flame, so it has safely shut itself down to prevent gas from building up.
Full guide for 22706
229 High Engineer
Your boiler has stopped heating because the flame inside went out while it was trying to run.
Full guide for 229on the Worcester Bosch Greenstar 28CDi
Central heating pumpSystem filterDiverter valveFan assemblyPrinted Circuit Board (PCB)NTC Sensor
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
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