High Lockout
5 red flashes on Baxi EcoBlue Advance Heat

Your boiler's internal memory chip has developed a communication fault, meaning the control board can no longer read its essential settings.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

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

Parameter storage unit (PSU) error.

What causes this fault?

This fault occurs when the small plug-in memory chip on the main control board fails or loses its connection. It is usually caused by an electrical glitch or internal wear and tear that prevents the boiler from identifying its own model and safety settings. Without these specific instructions, the boiler shuts down immediately as a safety precaution.

Engineer required

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

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