High
70 on Vokera Syntesi 25

Your boiler is having trouble reading the temperature of the water being sent to your radiators, which has caused it to stop heating your home to stay safe.

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

flow NTC error (2nd CH)

From this model's manual
Verified against the Vokera Linea He 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.

What causes this fault?

This fault occurs when the boiler's internal computer experiences a momentary communication glitch or receives an inconsistent reading from one of the temperature sensors. It acts like a temporary digital 'hiccup' where the main control board becomes briefly confused by the data it is receiving. If the issue persists, it usually points to a failing electronic control board or a sensor that is starting to wear out.

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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