How much does it cost to fix Saunier Duval error code Boiler Lock-out?

Typical repair cost for the Saunier Duval Boiler Lock-out fault is £120-300 including labour.

Boiler Lock-out High

Saunier Duval Boiler Lock-out Fault Code

Q: What does the Saunier Duval Boiler Lock-out fault code mean?

Your boiler has stopped working because it failed to start or stay lit, meaning your heating and hot water will not function.

Also written as BOILERLOCKOUT — same fault.

The Saunier Duval Boiler Lock-out fault code means: your boiler has stopped working because it failed to start or stay lit, meaning your heating and hot water will not function.. It appears on 1 Saunier Duval model in our database.

Technical description: Can be caused by: Insulating gas valves turned off; Ignition electrode dirty or broken; Gas valve faulty; Overheat thermostat faulty or boiler temperature over 100°C; Flue thermostat faulty or in open circuit; Flame polarity reversed; Ionisation electrode dirty or broken; Condensate siphon not draining; or Ignition unit faulty

Typical repair cost £120-300 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Saunier Duval models that show the Boiler Lock-out fault code

Click a model for the full fault code list and model-specific repair notes.

Semia Condens F30 E Repair: £120-300

Source

Saunier Duval Boiler Lock-out fault code information on this page is sourced and cross-checked against the official Saunier Duval service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026