750 High
Your boiler has disabled the central heating because it has detected a configuration error or a communication failure with your thermostat and heating controls.
Technical description: All heating zones locked
Typical repair cost: £90-180 (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 750 — no call-out fees, no surprises.
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Parts commonly replaced
- External heating controller
- PCB (Main Circuit Board)
- Wiring harness
*Affiliate links — we may earn a commission at no extra cost to you.