High
24 on Saunier Duval Ecosy

Your boiler's temperature sensors have been swapped during a recent repair or installation, causing the system to misread the water flow.

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 heating flow thermistor and heating return thermistor are connected the wrong way round.

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

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