High
420 on Chaffoteaux Flexiflame 140

Your boiler has detected a critical internal error regarding its heat output settings and has shut down to prevent damage.

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

Output 122.1 kW (Flexiflame 420)

From this model's manual
Verified against the Chaffoteaux Flexiflame 140 installation & service manual, page 24.
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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Related fault codes

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