High
F.84 on Vaillant Atmomax

Your boiler has noticed that its internal temperature sensors are giving conflicting or illogical readings, suggesting they are broken or incorrectly installed.

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

Error with flow/return temperature sensor temperature changing error

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.22View →F.23View →F.24View →

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