Sometimes an engineer will have a personal internal change during their career in which their professional path and interests start to veer from a product-thinking environment to a market-thinking environment (inward focus vs outward focus). It would be recommended to get certified in product management and even think about getting a Master's Degree in Business Administration if this is a path you'd like to pursue.
This can be a great career choice, as an engineer already has the technical background and understands the technology. It would be good to read books, blogs, and go to events pertaining to product management. Finding a mentor that has been a product manager for a few years would be excellent as well, as he/she can answer questions and help guide you through the process.