High
F84 on Heatline Compact 24

Your boiler is confused because its temperature sensors are giving conflicting readings or are not properly connected, causing it to stop heating your home to prevent potential damage.

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

Permanent temperature difference between fl ow and return heating sensors. Inverted or disconnected fl ow and return heating temperature sensors. Defective temperature sensors

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

F83View →F85View →

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