235 High
Your boiler's internal computer parts are unable to communicate with each other due to a software mismatch.
Technical description: Incompatible heat control module (HCM) software versions – control box needs latest software
Typical repair cost: £180-450 (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 235 — no call-out fees, no surprises.
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Parts commonly replaced
- Heat Control Module (HCM)
- Main PCB (Printed Circuit Board)
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