High
F.01 on Vaillant aquaPLUS

Your boiler has stopped working because one of its internal temperature sensors is unable to send a signal, meaning the system cannot tell if it is safe to heat the water.

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

Return NTC: NTC broken; NTC cable broken; Defective connection at NTC, Defective connection at electronics | Return-NTC cable defective/broken NTC faulty

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.00View →F.10View →F.11View →

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