12 Medium
Your boiler has lost connection with the sensor that monitors the temperature of your hot water cylinder, meaning it may not know when to heat your water.
Technical description: Cylinder sensor fault (FlowSmart only)
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 12 — no call-out fees, no surprises.
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Parts commonly replaced
- Cylinder NTC sensor
- Sensor wiring harness
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