How much does it cost to fix Saunier Duval error code Safety lock-out?

Typical repair cost for the Saunier Duval Safety lock-out fault is £80-120 including labour.

Safety lock-out High

Saunier Duval Safety lock-out Fault Code

Q: What does the Saunier Duval Safety lock-out fault code mean?

Your boiler has detected trapped air bubbles that are preventing it from running safely, so it has shut down to protect itself.

Also written as SAFETYLOCKOUT — same fault.

The Saunier Duval Safety lock-out fault code means: your boiler has detected trapped air bubbles that are preventing it from running safely, so it has shut down to protect itself.. It appears on 1 Saunier Duval model in our database.

Technical description: The boiler will go into safety lock-out if air is not properly purged from the system during filling.

Typical repair cost £80-120 (including labour)

DIY fix possible

Check your radiator valves and make sure there are no leaksUse a radiator key to bleed any trapped air from your radiators until water flows out steadilyOnce bled, check your boiler pressure gauge and use the filling loop to top it back up to 1.5 barReset the boiler using the button on the control panel

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Saunier Duval models that show the Safety lock-out fault code

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

Sylva Repair: £80-120

Source

Saunier Duval Safety 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