E99 High
Your boiler has detected an electrical fault with the sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety.
Technical description: Flue sensor short circuit – check connections to flue sensor are in place
Typical repair cost: £120-£220 (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 E99 — no call-out fees, no surprises.
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Parts commonly replaced
- Flue Gas Thermistor
- Wiring Harness
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