What does the Viessmann 35 fault code mean?

Your boiler has failed to ignite or stay running, meaning you currently have no heating or hot water because the burner is not firing.

How much does it cost to fix Viessmann error code 35?

Typical repair cost for the Viessmann 35 fault is £120-350 including labour.

Check if your gas supply is active (test a gas hob or check your meter credit)

Boiler does not activate

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Almost always a stuck diverter valve on combis.

Lockout fault with a reset-needed pattern.

Older boilers — thermocouple, draught, gas supply.