E 90 High
Your boiler has detected an issue with how it mixes fuel and air for combustion, meaning it cannot operate safely or efficiently.
Technical description: Error in regulating combustion – possible error with the calibration values chimney gas valve and board.
Typical repair cost: £180-450 (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 E 90 — no call-out fees, no surprises.
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Parts commonly replaced
- Main PCB (Control Board)
- Gas Valve
- Electrode
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