Technical description
Overheating in zone 2
What causes this fault?
This fault occurs when the water temperature in your second heating zone exceeds safe limits, prompting the boiler to shut down to prevent damage. It is usually caused by a physical blockage in that specific part of the system, a failed zone valve that won't open, or a pump that isn't circulating the hot water away from the boiler quickly enough.
This issue often surfaces during the first cold spell of autumn when secondary heating zones are switched back on after being idle all summer.
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.