F91 - actoSTOR module sensor/actuator fault

What does F91 mean?

This fault indicates a problem with a sensor or an actuator component within the actoSTOR module itself. It suggests an internal issue with the module's hardware, affecting its ability to function correctly.

• Internal defect within the actoSTOR module's sensors or actuators.
• Poor connection or power supply to the actoSTOR module.

Click steps to track your progress.

1. 1

   Check that the actoSTOR module is securely connected to the Vaillant Ecotec Plus Boilers.

2. 2

   Ensure the boiler's main power supply is stable and consistent.

3. 3

   If the issue persists, the actoSTOR module may need servicing or replacement by a qualified heating engineer.