Red flashing light High

Saunier Duval Red flashing light Fault Code

Also written as REDFLASHINGLIGHT — same fault.

The Saunier Duval Red flashing light fault code means: your boiler has detected a general issue and has entered a safety lockout mode.. It appears on 2 Saunier Duval models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: General fault indicator. Reset the boiler by turning the On/Off switch to ( 0 ), waiting five seconds, and turning back to ( I ).
Typical repair cost £100-250 (including labour)

DIY fix possible

Locate the On/Off switch on the boiler control panel.Turn the switch to the (0) position and wait for five seconds.Turn the switch back to the (I) position to attempt a system reset.

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Saunier Duval models that show the Red flashing light fault code

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

Source

Saunier Duval Red flashing light 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