High
40 on British Gas RD 430i

Your boiler has detected an internal electronic failure or a communication error between its main control components.

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.

What the manual says

Manufacturer manual

Heat output: 11.0 kW | Heat input: 11.1 kW | Gas vol. flow rate: 19.4 (l/min at tV/tR = 80/60°C)

From this model's manual
Verified against the British Gas Rd 430i System installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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