High
47 on Alpha E-Tec 20S

Your boiler is getting too hot inside its exhaust path, so it has automatically turned down its power to prevent any internal 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

Reduced burner output: Flue thermostat has sensed high flue gas temperature (110°C) and reduced the burner output to prevent damage

From this model's manual
Verified against the Alpha/Alpha E Tec S 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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Related fault codes

E03View →

All 29 fault codes on the E-Tec 20S

Seeing a different code? Every code this model can display, in one place.

0102030405060810121516202324252931373843455160617576nSr

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