70 High
Your boiler has detected a communication error between its internal temperature sensors, which means it cannot safely monitor the water temperature and has shut down as a precaution.
Technical description: Return/flow sensorExchange from possible wiring fault
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 70 — no call-out fees, no surprises.
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Parts commonly replaced
- Flow Thermistor
- Return Thermistor
- Wiring Harness
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