D1 240 High
Your boiler has detected a fault with the sensor that monitors the temperature of the water returning to the unit, causing it to stop the heating system for safety.
Technical description: Return sensor error – sensor may be wet or damaged
Typical repair cost: £110-190 (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 D1 240 — no call-out fees, no surprises.
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Parts commonly replaced
- Return Water Temperature Sensor (NTC Thermistor)
- Wiring Harness Connector
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