BoilerFaultCodesTechnical description
1 With boiler off & system cold, fill system to 1.0bar. 2 Bleed radiators, refill system to 1.0bar. 3 If fault persists, contact installer.
What causes this fault?
This fault occurs when the boiler's internal sensors detect that water is not moving through the unit, which is a safety mechanism to prevent the components from overheating. The most common reason is a simple drop in system pressure caused by a small leak or air trapped in the radiators, though it can also be triggered by a blockage or a failing pump. Essentially, the boiler has detected it is 'running dry' and has shut down to protect itself from damage.
This issue often appears in autumn when the heating is turned on for the first time after summer, as air bubbles can settle or small leaks can develop while the system is dormant.
Engineer required
This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.