It depends on the organization's culture, of course. In some orgs, managers are expected to focus purely on personnel and/or project management — they may as well have no prior engineering background. Outside of these cultures, however, engineering managers should continue to code. It's just that the nature of this coding changes.

I wrote about this awhile back. But the gist is that it's important for managers to maintain familiarity with the tools that their engineers are using. It's also part of a manager's job to unblock their engineers, and so they can tackle some of the "grunt" work — config changes, dashboards and alerts, etc. But the key is that their coding should always be outside of the critical path.