High Lockout
F.70 on Vaillant ecoMAX

Your boiler's control board has lost its identity settings, meaning the internal computer no longer recognizes which model of boiler it is supposed to be controlling.

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

Invalid device specific number (DSN)

What causes this fault?

This fault occurs when the boiler's main control board loses its memory of which specific model it is installed in. The most common reason is that a new circuit board has been installed but not yet programmed with the correct code, or an electrical surge has corrupted the board's internal settings.

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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Related fault codes

F.61View →F.62View →F.63View →F.64View →

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