ON ON ON High
Your boiler has detected an internal electrical communication problem between its main control components.
Technical description: Low voltage wiring harness error
Typical repair cost: £120-280 (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 ON ON ON — no call-out fees, no surprises.
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Parts commonly replaced
- Wiring harness
- Printed Circuit Board (PCB)
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