First, welcome to the forum!
I've never heard of a 2012 KC with a DPF, that's new - the last model I've heard of with a DPF was the early 2010 STX dual cab auto (the last of the Spanish 126kW models). If yours had a DPF, it would be interesting to see if auggie (a user here on this forum) could organise some sensor replacements for you to stop the car from doing regens.
In any case, with or without a DPF, the king cabs were always a little thirsty. Rumour has it that there's a software upgrade for the ECM to alleviate this, but getting the Nissan internal reference so that you can say to your dealer "Look up TSB number x" to get the fix in your car isn't as easy as it might seem.