Lot of great comments here already. As an engineering manager, I will just tell you that the fact you're even asking this question means you're on the right path. Anyone I have ever had to PIP was showing signs of not caring or trying to do well. If you are open to learning and willing to make the effort, then any company worth its salt will foster that and not make you feel inferior.

EDIT: Oh and I just want to second the top comment in that any "senior engineer" suggesting you "shouldn't be asking that question any more" should be fired immediately. Willingness to admit uncertainty is a critical quality in a good engineer, and fuck anyone who makes you feel inferior for asking an honest question.

EDIT2: By the way, I lost thousands of dollars by misprogramming a fraud rule once. This shit is hard, don't be hard on yourself.