High
Er.5 on Vaillant Thermocompact

Your boiler is struggling to read its own temperature because one of its internal sensors is disconnected or has stopped working correctly.

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

Flow-NTC / Return-NTC / Warmstart-NTC*

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.01View →F.20View →

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