High
F.11 on Vaillant Turbomax Plus

Your boiler has detected an electrical fault with the sensor that monitors the temperature of the water returning from your radiators, meaning it has safely shut down to prevent potential overheating.

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

Short circuit - return-NTC (<130°C) | NTC-plug shorted to casing, NTC defective

From this model's manual
Verified against the Vaillant Turbomax Plus installation & service manual, page 40.
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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