The human machine is not programmed in the traditional sense, it's learned to a large extent. Guilt is a signal that some behavior should be changed/relearned/reprogrammed.

The open question is why and how humans can "feel" guilt. How can a machine have a subjective experience at all? What is a subjective experience? This is the so-called "hard problem".

Because it's the source of the problem to be correct. That's it. Which part of this car is faulty? Same thing.