Regen AGAIN :-(

DEF should be injected pretty much any time the engine is running. The manufacturers have some leeway in cold climates to allow engine coolant/heaters to warm the DEF system but it must be operational within something like 45 minutes. I can't quite remember the exact number.

Contrary to popular belief DEF and the SCR system have nothing to do with regeneration. Regeneration is strictly in the DPF to catalyze the soot. The DEF injector is located downstream of the DPF, just before the SCR catalyst. The DEF simply reacts with the SCR catalyst to convert NOx to less harmful substances.

 

I drive a 2016 Volvo it had 404k miles on it when I got it, in the 30k miles I've put on it in the last 8 weeks it only needed a parked regen once... And that was only because I got a tank of bad def.

The previous truck I had got to the point that the last run before we replaced the dpf I had to stop every 200 miles and regen... That made for a long run across the country and back.

 

I can’t speak to the affects of idle time and how that changes things. If you’re running one of these 2010 and later motors in highway service, I’d be concerned that the passive regens are not enough to keep the Soot buildup down in the DPF. I’ve driven a Volvo D13, Cummins, and the new A26 motor. I’ve never had to do a parked regen, even in the Volvo where I had idle time as a company driver with no APU.
When I was a dispatcher at JBHUNT when the SCR motors came out, that was the big selling point, that we would no longer have to force drivers to stop and do a parked regen and reduce productivity.
The only literature I have found that mentions parked regens as a somewhat normal occurrence were in severe service service, off road, heavy haul, P&D, or heavy PTO use applications. You haven’t had complications from it and your truck isn’t very old yet. I’d be concerned that passive regen isn’t keeping up with the soot buildup.