BoilerFaultCodesVokera A 08 Fault Code
Also written as A08 — same fault.
The Vokera A 08 fault code means: your boiler has sensed that the water returning to it from your radiators is too hot, causing it to shut down to prevent damage to the system.. It appears on 2 Vokera models in our database.
Technical description: Return temperature too high, temperature differential too high, return thermistor fault
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Vokera models that show the A 08 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera A 08 fault code information on this page is sourced and cross-checked against the official Vokera service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026