BoilerFaultCodes.com
con High Lockout

Your boiler's internal computer brain is unable to talk to the front display panel, meaning the system cannot receive instructions to provide heating or hot water.

Call an engineer soon

Book a Gas Safe engineer within 24–48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: No communication with the printed circuit board: Communication fault between the display and the printed circuit board in the switchgear box

What causes this fault?

This fault occurs when the 'handshake' between the boiler's main control board and the front display panel is interrupted. The most common reason is a loose or damaged connection cable internally, though it often signifies that the electronics have suffered a surge or a component failure on one of the boards.

Typical repair cost £180-450 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Protect yourself from future repair bills

A boiler cover plan would cover faults like con — no call-out fees, no surprises.

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