New to me truck purchase help. Engine light is on.

You better hope your mechanical skills are legit, or you are willing to learn how to maintain and fix most DEF problems. Otherwise, the shop will want at least $150 per hour on labor, not including parts or even the days you will waste waiting for your truck to be ready. I’ve been there before, and my truck is a 2014 Freightliner Cascadia. Good luck!