High
H 4 on Ideal Isar M30 / M100

Your boiler has detected a critical internal error that prevents it from starting until a qualified heating engineer resets or repairs the 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

FAULT FINDING CHART MAIN MENU CODE - GO TO FRAME 68

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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