High Lockout
C2 on Keston S30

Your boiler’s internal computer chip has encountered a communication error or is missing, preventing the system from running safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

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

Technical description

Boiler Chip Card (BCC) fault

What causes this fault?

This fault occurs when the boiler's main control board loses its connection with the small plug-in memory chip that tells the unit exactly how to operate. The most common reasons are a loose connection due to vibration, a malfunction within the chip itself, or a hardware failure on the main circuit board that prevents it from reading the chip's data.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

C0View →L2View →

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