BoilerFaultCodesThe 6 most common faults
Your boiler has detected that the water pressure inside the system is currently too high for it to operate safely.
Locate a radiator positioned in a room where you can easily drain a small amount of water.Using a radiator bleed key, turn the valve slightly to release a small amount of water into a container until the pressure gauge on the boiler drops into the green zone (usually 1.0 to 1.5 bar).Close the radiator bleed valve tightly once the pressure has stabilised.
Your boiler has paused because either the water pressure in your system is too low or the water is not circulating properly between your radiators and the boiler.
Check the pressure gauge on the front of your boiler; if it is below 1.0 bar, use the filling loop to top up the pressure to 1.5 barEnsure all your radiator valves are fully openSwitch the boiler off at the fused spur for 30 seconds and then back on to reset the system
Your boiler has stopped working because the water pressure inside the system is too low.
Locate the filling loop, which is usually a flexible silver hose connected under your boiler.Open the valves at both ends of the hose to allow water into the system.Monitor the boiler's pressure gauge until it reaches between 1.0 and 1.5 bar, then securely close both valves.
Your boiler has detected that there is not enough water circulating inside the system to carry the heat away safely, so it has turned itself off to prevent damage.
Check your boiler's pressure gauge on the front panel; it should be between 1 and 1.5 bar.If the pressure is below 1 bar, locate the filling loop (usually a silver braided hose under the boiler).Open the valves on the filling loop to allow cold water into the system until the gauge reaches 1.5 bar, then firmly close both valves.
Your boiler is trying to start but cannot light the flame, which means you currently have no heating or hot water.
Full guide for F28Your boiler is failing to light the internal flame needed to produce heat or hot water.
Full guide for S.23on the Heatline Monza
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 Heatline 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