BoilerFaultCodesThe 6 most common faults
Your boiler has likely experienced an internal electrical fault or a component failure that has caused a safety fuse on the main control board to blow.
Why it happens: This fault occurs when an electrical surge or a component failure causes a safety fuse on the main control board to blow, cutting power to prevent further damage. The most common reason is a seizing water pump that is drawing too much current or a short-circuit within the boiler's internal wiring. As a result, the boiler shuts down completely to protect its sensitive electronic parts.
Full guide for F2Your boiler has stopped because the water pressure inside the system has dropped too low to operate safely.
Locate the external filling loop, usually a silver braided hose under the boiler.Open the valves on the filling loop to allow cold mains water into the system.Watch the pressure gauge on the front of the boiler until the needle reaches the green zone (ideally 1.0 to 1.5 bar).Close the filling loop valves tightly and ensure the boiler resets itself.
Your boiler has stopped working because the water pressure inside the heating system has dropped too low to operate safely.
Locate the filling loop, which is usually a flexible metal hose with one or two valves underneath the boiler.Gradually open the valve(s) to allow mains water into the system while watching the boiler's pressure gauge.Stop filling once the needle reaches the green zone, typically between 1.0 and 1.5 bar, then tightly close the valve(s).
Your boiler has lost the ability to accurately measure the temperature of the water flowing through it, so it has shut down to ensure safety.
Full guide for F.00Your boiler has stopped working because a sensor that measures the temperature of the water coming back into the system has sent an incorrect reading.
Full guide for F.01Your boiler has stopped working because it is unable to accurately measure the temperature of the water flowing through the system due to a faulty sensor connection.
Full guide for F.10on the Glow-worm Ultimate3 Combi
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 Glow-worm 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.
Affiliate links. We may earn a commission at no extra cost to you.