High
70 on Alpha E-Tec Plus 28

Your boiler is struggling to detect water temperature correctly, which is likely caused by a blocked system, loose wiring, or a faulty sensor prevented it from heating properly.

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/flow sensor error (return reading higher than flow) - Possible wiring fault, sensors incorrectly fitted, system blocked

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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