High
A08 on Vokera Mynute i

Your boiler has detected that the water temperature returning to it is unusually high or that the sensors are not reading the temperature correctly, causing it to 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

Return thermistor fault / Return thermistor over temperature / Temperature differential inverted

From this model's manual
Verified against the Vokera Mynute I installation & service manual, page 7.
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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