BoilerFaultCodesVokera AL71 Fault Code
The Vokera AL71 fault code means: your boiler has detected an issue with the sensor that measures the temperature of the water leaving the unit, meaning it cannot safely regulate heat.. It appears on 8 Vokera models in our database.
Technical description: Primary (flow) thermistor fault
What causes the Vokera AL71 fault?
This fault occurs when the boiler's internal computer loses communication with the sensor that monitors the temperature of the water sent to your radiators. The most common reason is that the sensor has either failed electrically due to age or has developed a loose connection, preventing the boiler from knowing if it is overheating. To prevent damage, the boiler will shut down immediately until the sensor is replaced or repaired.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Vokera models that show the AL71 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vokera AL71 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 27 April 2026