ISB in limp mode/No Codes

[mayhem1]

Have a 2011 Ford F650 Cummins ISB that came in with DEF tank issues which turned into multiple codes. After repairing tank(changed tank module), cleared codes and did a regen. Had a NOX sensor problem. Replaced and there are no codes at all on engine. Body controller has a cruise switch code and the Wabco brakes have two codes, but nothing that I think would put it in limp mode(10 MPH). I went in and reset dpf filter. It ran down the road once and now it stays in limp mode. Do I need to get the ECM reflashed? There is no telling how long they have operated this truck with def tank problems...I'm sure till it would not run period. I'm stumped.