What does the Chaffoteaux Red lockout indicator bulb 29 fault code mean?

Your boiler has failed to light the flame three times, so it has purposefully shut itself off for your safety.

Chaffoteaux Red lockout indicator bulb 29 Fault Code: What It Means & How to Fix It

Typical repair cost for the Chaffoteaux Red lockout indicator bulb 29 fault is £120-250 including labour.

If a flame is not detected, after 8 seconds, the security solenoid closes and shuts off the gas. The red lockout indicator bulb 29(fig. 5) will show.

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