"To follow the code" means to adhere to a set of rules or principles, usually within a specific context or community. It suggests that one should act in accordance with the established guidelines or moral standards. Full definition
Beyond the fact that the Realtor does not follow the code of ethics, this short sale is more than likely going to be flat out rejected by the lender. (massrealestatenews.com)
A UI Developer builds software applications by following coding standards. (resumesamplesdownload.in)
Since these practices are becoming more common, it's kind of a shock when companies don't follow those codes of conduct. (businessinsider.com)