High
AC on Worcester Bosch Highflow 300

Your boiler has lost communication with one of its internal control units, meaning it cannot properly manage your heating or hot water functions.

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.

What the manual says

Manufacturer manual

Module not detected (either heat or water)

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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All 57 fault codes on the Highflow 300

Seeing a different code? Every code this model can display, in one place.

6A6C6d9UA1A4A5A7A8AdB1b2b3b4b5b6b7C1C4C6D1d3d5d6E2E5E9EAF0F1F7FAFdH1H4H7H9HCHeatbank Overheat StatHot water high limit statNo codeoverheat lock-out statePOINT BPOINT CPOINT DPOINT EPOINT FPOINT GPOINT HPOINT IPOINT JPOINT KPOINT NS9Safety limit statSy

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