70 High
Your boiler has detected a problem with the sensor that monitors water temperature as it returns from your heating system, causing the unit to stop running for safety.
Technical description: Return flow sensor error
Typical repair cost: £120-£200 (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 70 — no call-out fees, no surprises.
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Parts commonly replaced
- Return NTC temperature sensor
- Wiring loom connector
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