BoilerFaultCodesThe 6 most common faults
Your boiler has switched itself off because it has reached an internally high temperature and needs a manual restart to clear the safety lock.
Why it happens: This fault occurs when the water inside the boiler exceeds a safe temperature limit, triggering a safety switch to prevent damage. The most common reasons are a pump failure that stops water from moving through the system or a build-up of debris blocking the internal heat exchanger. It can also be caused by a faulty sensor misreading the temperature even if the boiler isn't actually too hot.
Locate the control box on the boiler unitIdentify the reset button on the bottom right-hand sidePress and hold the button for a few seconds to clear the lock-outCheck that your radiator valves are open to allow water to circulate
Your boiler has switched itself off because the internal fan that clears exhaust gases has stopped working.
Why it happens: This fault occurs when the boiler's control board sends power to the fan but does not receive any movement in return. The most common reason is that the fan motor has burnt out or seized up due to age, preventing it from clearing combustion gases so the boiler can safely fire up.
Full guide for POINT GYour boiler is failing to ignite the burner at the required power, meaning it cannot provide heating or hot water.
Why it happens: This fault occurs when the boiler's control system attempts to fire the burner at full power but fails to detect the necessary electrical signal or gas pressure. It is typically caused by a failing gas valve that cannot open fully or a fault within the internal control box that prevents power from reaching the ignition components. In some cases, a loose or damaged wiring connection between these two parts is the root cause.
Full guide for POINT DA small cooling fan inside the boiler's control panel has stopped working, which prevents the system from starting to ensure the electronics do not overheat.
Why it happens: This fault occurs when a small dedicated cooling fan located inside the boiler's main control box fails to spin up. Over time, the fan motor can burn out or become clogged with dust, preventing it from cooling the sensitive electronic components. As a safety precaution, the boiler will refuse to ignite to prevent the circuit board from suffering permanent heat damage.
Full guide for POINT EYour boiler is failing to circulate water when you turn on a hot tap, meaning you will likely have no hot water.
Why it happens: This fault occurs when the boiler detects that water isn't moving through the internal tank even though you have turned on a hot tap. The most common reason is a seized or failing internal pump, but it can also be caused by a faulty flow sensor that fails to tell the boiler to start the heating process.
Full guide for POINT HYour boiler is struggling to switch between providing heating and hot water, meaning you likely have no hot water available.
Why it happens: This fault occurs when the boiler's internal brain tries to switch the water flow from your radiators to your hot taps but receives no response from the switching mechanism. The most common reason is that the small electric motor responsible for moving the valve has burnt out or the internal valve itself has become seized due to a buildup of debris and sludge within the system.
Full guide for POINT Ion the Worcester Bosch Highflow 250
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