713 Medium
Your boiler has detected a faulty temperature sensor in the third heating zone, meaning it cannot accurately monitor the water returning from that specific part of your home.
Technical description: Return sensor defective (zone 3)
Typical repair cost: £90-160 (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 713 — no call-out fees, no surprises.
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Parts commonly replaced
- Zone 3 Return NTC Temperature Sensor
- Wiring harness
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