If ethics are poor at the top, that behavior is copied down through the organization. ~Robert Noyce
If you want to instill good work ethics among your team, you must lead them from the front. Until and unless you (or the people at the managerial level) don't set the benchmark for your team, you can not expect to see great results. It is crucial to have an organizational code of conduct and ethics, but it is more important to ensure everyone abides. Humans perceive through their senses and act accordingly. Therefore, to ignite the light of dedication and commitment, you must be the torchbearer.
In other words, you should always 'Practice what you preach.' We are more likely to follow or do something relevant to us and have a good motive behind it. When you motivate your teams or lead them, you should always go back and forth and see if you have set a good example.