What does the Vaillant S.46 fault code mean?

Your boiler is struggling to keep its flame steady while running at a very low power setting and has temporarily shut down to protect itself.

How much does it cost to fix Vaillant error code S.46?

Typical repair cost for the Vaillant S.46 fault is £150-300 including labour.

Comfort protection: Minimum load, loss of flame (Comfort protection mode, flame loss at minimum load)

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

Work through these before the call-out.

Lockout fault with a reset-needed pattern.

Older boilers — thermocouple, draught, gas supply.