High Lockout
E135 on Baxi 600 Combi (range)

Your boiler has lost its connection to the gas supply due to an internal electronic communication failure, meaning it cannot ignite to provide heat or hot water.

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

Interruption of gas supply (internal error)

What causes this fault?

This fault occurs when the boiler's main control board loses the ability to communicate with the gas valve, preventing the system from releasing fuel for ignition. The most common reason is a malfunctioning printed circuit board (PCB) or a loose connection in the internal wiring harness. In some cases, the gas valve itself may have developed an electrical fault that keeps it from responding to the boiler's commands.

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

E125View →E128View →E133View →

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