What does the Saunier Duval F4 fault code mean?

Your boiler is failing to stay lit because it cannot confirm that the flame has actually started, causing it to shut down for your safety.

How much does it cost to fix Saunier Duval error code F4?

Typical repair cost for the Saunier Duval F4 fault is £120-250 including labour.

The burner lights, then goes out. Flame not being detected (Check continuity between flame sense electrode and terminal H2.4).

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.

Safety-critical — turn off, read this.

7 signs repair isn't worth it anymore.