What does the Vaillant F.29 fault code mean?

Your boiler has lost its flame while running and cannot manage to relight itself, likely due to a problem with the gas supply.

How much does it cost to fix Vaillant error code F.29?

Typical repair cost for the Vaillant F.29 fault is £100-350 including labour.

Check if other gas appliances in your home, like a hob, are working correctly.

Flame extinguished re-ignition unsuccesful | Gas supply absent or insufficient

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

Lockout fault with a reset-needed pattern.

Older boilers — thermocouple, draught, gas supply.

Safety-critical — turn off, read this.