E 77 Emergency
Your boiler has detected an issue with its internal combustion levels and cannot regulate the gas flame safely.
Technical description: Current values reached – check combustion values and CO2 calibration, try resetting the boiler if this fails. Either the board or the valve will need replacing.
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 77 — no call-out fees, no surprises.
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Parts commonly replaced
- Gas Valve
- Main Printed Circuit Board (PCB)
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