Good morning, I have in the workshop this citroen c4 with the error code P1A9C, Energy Accumulator.Health Status Fault.

the car starts well, the start and stop does not work and the service light is always on in the ignition

the only thing is that this vehicle has been idle for about a year according to the customer

The battery has been tested and is OK.

If I remember correctly, this model was fitted with a capacitor to give more 'starting power', which could be the cause of the fault,

since it has been stationary for a long time and the capacitor has lost its ability to recharge?