It is possible to have a faulty master cylinder.
But the first step would be to make sure the brake system has been bled properly.
Even with little amount of air the pedal will be soft.
Keep in mind that ABS brake systems require a scan tool to bleed properly.
Here is a helpful video that goes over the steps:
I have attached the instructions for ABS brake bleeding below.
Please let me know if you have any questions.
Images (Click to make bigger)
Tuesday, November 2nd, 2021 AT 8:47 PM