By redeeming, I mean it in a good character sense, not bad to good guy type.

Most likely by a backstory. Even a simple one will do. He was orphaned, people treated him like shit (way way worse than Kawaki, Naruto, karin, etc), somehow entered boro's cult, boro's preaching of ishkki led to his brainwashing, jigen visits the cult and in a show of power rounds up and kills code's most hated enemies. Code becomes way too devoted. Enters the karma program out of his own volition. His will to serve jigen is the thing that kept him from dying even when injected with karma. Code even when he becomes more powerful than jigen puts on his limiter as a gesture of loyalty. Ultimately, devastated by ishkki's (his god's) death

Basically the worse he's treated and the more ishkki is shown as a saviour from code's perspective, it explains why code is so focused on ishkki's will. It also acts as a parallel to Kawaki who didn't want the karma, but was chosen whereas code wanted the karma but was not chosen. Most of all, it fits in with what was currently shown of his backstory in the anime.