High
F.77 on Viessmann Vitodens 200-W B2HF System

Your boiler's internal computer brain is having trouble reading or saving its settings, causing the system to stop working for safety.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Data memory burner control unit

From this model's manual
Verified against the Viessmann Vitodens 200 W B2hf System installation & service manual, page 90.
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 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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