Low
SH on Worcester Bosch CDi Classic

Your boiler is currently running a maintenance check at its maximum power, which is a normal process and not a fault with the system.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

The display (C) will alternate between SH and the central heating flow temperature. Performance test mode (maximum output) is active.

Shared across the Greenstar 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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All 15 fault codes on the CDi Classic

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

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