Medium
d8 on Viessmann Vitodens 242-F B2UA

Your boiler has detected an external signal or safety switch connected to it that is currently reporting an error, meaning the system has paused to prevent operation until the external issue is resolved.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

What the manual says

Manufacturer manual

Input DE3 at extension EA1 reports a fault

From this model's manual
Verified against the Viessmann Vitodens 242 F B2ua installation & service manual, page 131.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

d7View →d9View →

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