Doosan HP375 / 425 Problems

I have 2 Doosan HP375/425 Compressors....

Issue 1 - 2018 Doosan less than 1000 Hrs.... Here are the Codes: SPN 1569 / SPN 5245 / SPN 91

I am pretty sure this is the DEF Head issue that is fairly frequent in them but the SPN 91 is a Throttle Position issue.... Is this related? The compressor is unusable because it is a RED Light Code.
Any ideas or thoughts on how to solve this would be great.

Issue 2 - 2014 Doosan HP375/425 - Non- Def machine - 3000 hrs - it was blowing couplings constantly - it went through 2 in 2 weeks. Spoke with a DOOSAN guy and he said probably an engine issue, motor is surging loading and unloading the coupling and causing an issue. Took to CUMMINS - 2.5 Months later and $4900.... they did some things, new ECU was the costly one, all the codes are gone but when I fire it up, it was still surging, RPMs not staying consistent.

Ideas on why it is blowing clutches and has anyone seen this before. Any help would be greatly appreciated.

My bad dude I just found this
First issue definitely your def header is faulty if you wanna be sure check the connector on the def header if you are getting a 5v reference on brown and red and brown and yellow (Don’t really remember color) wiring good def header bad
Second issue with the coupler going out will be lack of maintenance or engine running like crap pretty simple.