20, 21, 22, 23, 24 High
Your boiler has detected a problem with one of its internal temperature sensors, which means it cannot safely measure how hot the water is and has stopped working as a precaution.
Technical description: Sensor fault S2
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 20, 21, 22, 23, 24 — no call-out fees, no surprises.
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Parts commonly replaced
- NTC Temperature Sensor (S2)
- Sensor wiring harness
- Printed Circuit Board (PCB)
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