High
F.01 on Vaillant Combi Compact 242EB

Your boiler has stopped working because an internal temperature sensor or its wiring has failed, meaning it can no longer safely monitor the water temperature.

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

The Flow NTC (Negative Temperature Coefficient Thermistor) cable is either defective or broken and needs to be replaced

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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