Paccar regen problem

Dpf is full.
Or bad sensors

 

It should regen automatically driving down the road. If your idling at night that could fill the DPF up by morning. Freightliner has automatic regening when parked. I believe Volvo does the same thing.

 

DEF wouldn't have anything to do with daily regens. The DEF system is an after treatment after the exhaust comes out of the DPF. Like @daf105paccar said, sounds like a sensor going bad or a DPF needing serviced. I'm guessing miles are in the 3-400k? Although, PACCAR motors were notorious for emissions problems years ago, so it depends on how old the truck is.

 

Excessive idling does cause the DPF to need a regen more often. The Pete I was in, it was recommended that if we had to idle due to temps, that we raise the idle to 1500 to help keep the DPF hot enough to regen itself. However, with the other issues you said it has, sounds like it needs to see Mr. Peterbilt.

And BTW, I have a Mack with an mDrive that won't go into neutral half the time, and I am in the shop for the 2nd time in 6 weeks, last time it was injectors, this time it's filling the crankcase with diesel, and they can't figure out why ...so they're not much better.

 

You need to start with this. With an active CEL this may be disabling or preventing a passive regen while driving. Lots of EGR and other faults will not allow regeneration while active.

As far as your trans issue ,start with the batteries and clean all cables and connections and have the batteries load tested. This a good place to start and often corrects intermittent shifting issues.