High
E6 on Viessmann Vitodens 200-W Combi

Your boiler has stopped working because there is not enough water flowing through the system to keep it running safely.

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

Air pressure limiter enables start (contact closed between terminals X8.10 and X8.11) fault: After approx. 51 seconds - Check fan cables and fan plug-in connections, check fan

From this model's manual
Verified against the Viessmann Vitodens 200 W installation & service manual, page 97.
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 boiler's internal sensors detect that water isn't moving through the unit fast enough to safely carry heat away from the burner. The most common reasons are a failing internal pump that can no longer push the water or a significant blockage within the main heat exchanger. It can also be triggered by a build-up of sludge in the system pipes that restricts overall flow.

This issue often surfaces in autumn when the heating is turned back on after a long summer break, as pump components can seize during periods of 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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