Worcester Bosch · Greenstar i System ErP

A8 boiler fault code

Greenstar i System ErP

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What A8 means

HCM invalid: the fitted HCM does not match the control box or display type (cause 361).

Gas Safe engineer: Contact a Gas Safe registered engineer for diagnosis.

If you smell gas, a CO alarm sounds, anyone feels unwell, or there is an unsafe flame, leave and call 0800 111 999 from outside.

Safe check

Note the code and any three-digit cause code shown. Do not remove the casing, adjust anything or keep resetting; contact a Gas Safe registered engineer.

When to contact an engineer

Contact a Gas Safe registered engineer for diagnosis.

Source and provenance