BoilerFaultCodesThe 6 most common faults
Your boiler has detected that there isn't enough water moving through the system, which is usually caused by a leak or a pump that has become stuck or worn out.
Check the pressure gauge on the fascia and top up to 1.5 bar if it is lowLook for any visible water leaks under the boiler or around your radiatorsCheck that all radiator valves and internal isolation valves are fully open
Your boiler has switched itself off because it has detected that the water inside has become dangerously hot or the system pressure is incorrect.
Check the pressure gauge on the front of the boiler is between 1 and 1.5 barIf the pressure is low, use the filling loop to top it upEnsure all radiator valves are fully openPress the reset button once the system has cooled down
Your boiler has stopped working because it cannot light the fuel required to provide heating and hot water.
Check if your gas or oil supply is turned on and that you have credit on your meterPress and hold the reset button for five seconds to see if the boiler restartsThaw your external condensate pipe with warm water if it is frozen during cold weather
Your boiler has shut down because the internal water temperature has become too hot for it to operate safely.
Check that all radiator valves are fully open to allow water to circulateEnsure your system pressure is topped up to between 1 and 1.5 bar on the gaugeReset the boiler using the reset button on the control panel
Your boiler has tried to light several times but cannot establish a steady flame, meaning it has shut down for safety.
Check if your oil tank has run out of fuelEnsure the oil supply valve on the tank is fully openPress the reset button once to see if the boiler restarts
Your boiler has experienced an internal electronics crash or software glitch that is preventing it from starting up properly.
Locate the main power switch for the boiler (usually a fused spur nearby).Turn the power off, wait for 30 seconds, and turn it back on to reboot the system.If the code persists, press and hold the 'Reset' button on the boiler fascia for five seconds.
on the Worcester Bosch Heatslave
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