OPn High
Your boiler has detected that a temperature sensor cable has disconnected or become faulty, preventing the system from monitoring water flow correctly.
Technical description: HP flow sensor open / HP return sensor open
Typical repair cost: £120-£220 (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 OPn — no call-out fees, no surprises.
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Parts commonly replaced
- Flow Temperature Sensor
- Return Temperature Sensor
- Wiring Loom
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