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.

Technical description

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

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

4-A5View →4-A6View →

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