Your boiler has shut down because it has detected an issue with a safety sensor or the pump that removes excess water from the system.

Contact thermostat triggered. The surface-mounted thermostat or the condensate pump has triggered.

What causes this fault?

This fault occurs when a safety device detects that water isn't draining away correctly or the system is getting too hot. The most common reason is a blockage in the waste water pipe or a failure in the external pump that pushes excess fluid out of the boiler. To prevent internal damage or a leak, the boiler automatically shuts down as a protective measure.