BoilerFaultCodesTechnical description
The display shows alternatively the CH flow temperature and 9A. The pump is blocked. See error E9.
What causes this fault?
This fault occurs when the boiler's internal pump is unable to spin, preventing hot water from leaving the unit. The most common reason is a build-up of black iron oxide sludge that physically jams the moving parts, or an electrical failure within the pump motor itself. Without a working pump, the boiler shuts down immediately to prevent the internal heat exchanger from overheating.
This fault is frequently seen at the start of autumn when heating systems are turned back on after being idle all summer, allowing settled debris to seize the pump.
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.