BoilerFaultCodesThe 6 most common faults
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the external filling loop or internal key under the boilerSlowly open the valve to let water into the system while watching the pressure gaugeClose the valve tightly once the needle reaches the green zone, typically between 1.0 and 1.5 bar
Your boiler has detected that the water pressure in your heating system is dropping much faster than it should, which usually indicates a leak somewhere in your pipes or radiators.
Check all visible radiators, valves, and pipework for signs of water leaking or damp patchesInspect the pressure relief valve discharge pipe outside the house to see if water is constantly drippingIf no leak is found, try repressurizing the system to 1.5 bar using the internal filling link and monitor if the needle drops again
Your boiler has stopped working because the amount of water inside your heating system has dropped below the required level.
Locate the internal filling link (a small lever or key under the boiler).Open the filling valve slowly until the pressure gauge on the front of the boiler reads between 1.0 and 1.5 bar.Close the valve firmly and wait for the boiler to automatically restart.
Your boiler has detected that the internal exhaust fan has failed to start or stopped unexpectedly, so it has safely turned itself off to prevent a buildup of fumes.
Full guide for 214Your boiler has detected that it is running dangerously hot and has shut itself down to prevent internal damage.
Full guide for 224Your boiler is trying to start but the flame is failing to light or stay lit, so it has safely shut itself down to prevent a gas build-up.
Full guide for 227on the Worcester Bosch Greenstar 4000
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
Avoid the next call-out bill
Monthly cover means no unexpected bills when your boiler breaks down.
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