another d13 with dpf issues

When did you last have injectors and cups done?

 

Very well could be the real issue. Have a different shop look at it if you can. Doesn’t sound like that shop is any good.

 

If you want to rule out the SCR box being plugged, you could get it cleaned out. I removed mine and took it in to get blown out, washed, and baked for around $400. You'll need to remove the two exhaust clamps, then put a low profile floor jack under it with some plywood or something. The SCR is bolted to the frame at the top of two bands, the bands run through some metal retaining clips on the SCR box, and it has some hooks on the bottom that hold it in place. It's very heavy and awkward, so just be careful when lowering it on the jack and wheeling it out. Once you get it out, you can have a helper lift it up with you. I ended up getting two boards and making a ramp to the tailgate of my pickup, then I just rolled it up by myself. When you put it back on, get new clamps and gaskets for the exhaust pipes.

The SCR box still might be bad somehow, but at least you'll know it's not plugged.

 

Disclaimer, I don't work on the Volvo platform but have worked on some Mack MP motors. First thing, a DPF doesn't plug itself up. It has to be getting excess soot or SCR is plugging causing excess back pressure readings @ DPF delta P sensor. Excess soot can be caused leaky HC doser, air management issues, or injector issues. Dealer can easily flow test a doser and see if it is leaking and correctly flowing. Air management would be like an "EGR tuneup". All sensors in EGR ducting need to be cleaned along with venturi tube and boost pressure and intake air sensors. Once this is all verified, next thing to check is injectors. In my experiences, over 600,000 miles is the life expectancy for Delphi injectors when they begin to slightly over fuel because of internal leakage in control valve. Truck runs fine and decent power, but more frequent regens start. Volvo is notorious for injector and cup issues. You have an engine out soot issue that needs solved.

 

It could be requesting a regen due to low SCR performance, not just a soot problem. I don't know what the code that was posted is for, but I assumed it was part of the bad DEF detected message.

My truck was having some issues where it would request a regen because of low SCR performance. I could usually drive through the derate and it would clear itself after 250 miles or so. There were times when it was the end of my day or I didn't have enough fuel, so I would force a regen and it would clear. I still suspect that I might have an injector issue, likely from a cheap reman that I purchased. The soot gauge stayed between the 20-40% range.

My solution was to take my old inlet NOx sensor and put it back on. I kept it around because it threw a code every 3 cycles or 150 miles that I could just plug in and clear without any derates, and I was tired of having to regen constantly. The original sensor code nor the low SCR performance code has not come back since, so who knows at this point.

 

Sounds like @loudtom had same issues of regens to keep SCR temps up for proper conversion efficiency. Do you have a print out of the codes? Yes, 7th injector. Like I said I don't work on Volvo platform. Have you looked at getting an OTR tool to pull codes and lift derates or PTT? OTR Reset Tool | Volvo & Mack