2013 ISX3 DEF issues

My 2015 Peterbilt 2013ISX3 SWVer. 09400047 over last few days has been throwing a number of codes, derated and shipped to Peterbilt to fix. Got truck back and within 150-200km codes FMI:18 SPN:4334 and FMI:2 SPN:4334 came up. Peterbilt says they don't even know what the code is because it doesn't match model truck numbers. (Crock of crap or truth? You can be the judge - personally I think it's crock). Intermittently SPN:1569 (engine derate) coming up and back off lasting anywhere from a few moments up to an hour that I noticed before going back off. I've read others posts and such that say 4334 (pressure sensor) is misleading stating the cause for this code is elsewhere. Anyone else go through these issues and have had successfully repaired their dosing system? Any help appreciated.

 

They said mine was electrical. Something about being wired wrong at factory. Whether that's a pile of crap or not, I don't know. It's been working good now since coming back after 2nd trip to Peterbilt.