High
F.11 on Vaillant ecoTEC Plus 610

Your boiler's temperature-monitoring system has detected a faulty signal, likely due to a loose wire or a broken sensor, preventing it from heating your home safely.

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

Shortcircuit: Returntemperaturesensor. NTCsensordefective,shortcircuitinthecableharness,cable/casing

From this model's manual
Verified against the Vaillant Ecotec Plus 610 installation & service manual, page 33.
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

F.10View →F.12View →

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