High Lockout
F.70 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler's computer and internal display screen are no longer communicating correctly because they haven't been configured to recognize each other.

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 and front display panel are unable to talk to each other correctly. It typically happens after a repair where a new part was installed but not programmed with the specific identity code required to match your exact boiler model.

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 →

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