Low
4-A4 on Worcester Bosch Greenstar 2000

Your boiler is simply letting you know that it is due for its routine annual service based on how long it has been running.

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

Service display / Inspection interval according to hours run: 0: switched off, 1: acc. to hours run, 3: acc. to elapsed time.

From this model's manual
Verified against the Worcester Bosch Greenstar 27cdi installation & service 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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4-A5View →4-A6View →

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