High Lockout
E42 on Remeha Avanta Plus 35c

Your boiler's main internal computer has developed a communication fault or electronic failure, preventing it from managing the heating system.

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

Internal control unit error

What causes this fault?

This fault occurs when the boiler's main control board suffers an internal electronic failure or loses the ability to talk to other sensors. The most common reason is a short circuit on the board or general wear and tear of the electrical components over time, which prevents the computer from safely managing the ignition and heating process.

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

E01View →E10View →E40View →

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