High
E9 on Worcester Bosch Greenstar Ri

Your boiler has got too hot and has automatically shut down for safety to prevent damage.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

What the manual says

Manufacturer manual

Safety limiter in flow has tripped.

From this model's manual
Verified against the Worcester Bosch Greenstar Ri installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety sensor to cut the power. It is usually caused by a pump failure that stops water from moving or a blockage in the system that prevents heat from being carried away fast enough. In some cases, air trapped in the heat exchanger can also cause a localized hotspot that trips the sensor.

This fault is more frequent in autumn when heating systems are first turned on after a long summer break, as pump components can seize due to inactivity.

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.

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