E23 High
Your boiler has detected a fault with the sensor that monitors exhaust gases, and as a safety precaution, it will not operate until this is fixed.
Technical description: Flue sensor damaged
Typical repair cost: £120-£210 (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 E23 — no call-out fees, no surprises.
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Parts commonly replaced
- Flue Gas NTC Sensor
- Connecting Wiring Harness
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