2 High
The boiler has detected that two internal temperature sensors have been swapped or are reading incorrectly, preventing the system from heating up safely.
Technical description: S1 and S2 interchanged
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 2 — no call-out fees, no surprises.
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Parts commonly replaced
- Flow temperature sensor
- Return temperature sensor
- Sensor wiring harness
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