B7 257 High
Your boiler's internal computer has developed a fault and can no longer communicate with the main control system.
Technical description: Control box or the heat control module HCM) is defective- the HCM and control box connections need to be checked
Typical repair cost: £250-450 (including labour)
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Protect yourself from future repair bills
A boiler cover plan would cover faults like B7 257 — no call-out fees, no surprises.
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Parts commonly replaced
- Heat Control Module (HCM)
- Printed Circuit Board (PCB)
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