Taking the plunge. My journey as an O/O.

Had a bit of an o #### moment on I-80 Westbound in Nevada shortly after leaving Utah.

30k lbs in the box, got hit with a massive rogue gust that pushed hard enough to tilt my cab pretty significantly. Don't think any tires left the ground, but it was definitely a pucker moment.

I tend to ride fairly close to the outside of the road, thankfully. If I ran to the center of the road, I might have hit the 4-wheeler beside me.

As it was, the 4 wheeler that was starting a pass dropped back fast and watched me for about 3 minutes before zipping past. He was either calling in my truck or watching to see if I was drunk, I guess. He was far enough into my wind shadow he might not have even felt the gust.

 

I checked the codes. No clear faults. Bad Def, nox emissions, and a 25% derate.

Ran a manual regen yesterday and that cleared the L2 engine fault. The L1 fault cleared about 300 miles into today's driving day.

Nothing I feel comfortable trying to work on, since none of the faults are clear.

 

Watch some videos and see if you would feel comfortable doing some of the easier stuff. It's possible that you're losing a half a day or more in downtime and paying someone $400+ to just remove two bolts and spend 15 minutes cleaning a part and reinstalling it(or more if they just decide to replace the part). Sometimes bolts can be stubborn, but that's usually because they're not taken off regularly and end up seizing. It's another good reason to take them off periodically rather than wait for 300,000 miles to do it.

If you're having regen troubles, it can't hurt to check/clean the hydrocarbon doser. If you're having NOx efficiency trouble, it couldn't hurt to check/clean the DEF doser. It's not guaranteed to fix the issue, but it makes sense to do the easy stuff yourself. The only exceptions I can think of is if you're accident prone, have a bad habit of breaking things, or dropping parts into hard to reach places.

Also you'll want to read the codes in SPN/FMI format. I still have no idea what an L1 or L2 code is.

 

SPN 3364 FMI 2
SPN 4364 FMI 18
SPN 5246 FMI 15

None of those codes indicate a specific issue, as noted above. I can't remember which is which.

L1 / L2 / L3 engine codes are the dummy lights.

L1 engine code is a single engine error LED lit. "Hey there might be a problem."
L2 engine code is two engine error LEDs lit. "Yup, you got a problem. Watch yerself."
L3 engine code is three engine error LEDs lit. "Screw you, driver, something's wrong and I'm shutting down."

I am certain that the problem is sensor related. I take 34's regularly, and up until a few months ago, the truck would go into an auto regen at least once every 34.

Now, the truck never goes into an auto regen. Whatever sensor tells the truck that an auto-regen is needed has failed. Sensor, wiring, electronics, or code, I don't know, but it's not a filter or injector.

 

I found all sorts of answer to those codes. Lots of things to try before getting reamed a new butthole at a dealer.

 

Which of those answers directly addresses a failure to start an automatic regen when in opti-idle state. Because that is the problem. The codes only confirm that the truck is not cleaning the DPF system as it should while I am on a 34.

 

I read it code be as simple as def crystals clogging the lines, pump, doser. You have to look up the codes and go from there. Rawze has a lot of info on those engines. I didn’t read anything about just on a 34. Take it to the dealer they’ll fix it.

 

My truck won't regen if there's an active fault code. If that's the case with your truck, then you should find out why NOx conversion is low. The sensor that is normally responsible for regens is the differential pressure sensor on the DPF. It is not related to NOx, it only measures the difference in pressure before and after the filter to estimate how plugged up the filter is.

It's possible that one of your NOx sensors is having trouble, but the only way to be certain is to hook up a computer and watch the ppm for irregularities. You can replace the sensors and hope it works, but if they're $500+ per sensor like Volvo, it's a lot of money to throw at a guess. Also consider that sometimes a new sensor can sometimes be faulty, especially cheap ones like you find on Amazon.

Keep your DEF tank topped off so there's less chance of poor quality causing the code. Then make sure there's no crystals building up on the doser, which messes up the spray pattern. Check for evidence of exhaust leaks, or even spray the connections with soapy water while the engine is cold. At this point, if the code persists, I would get a reset tool or take it to a good shop to get a proper diagnosis. Even with the tool, if you keep having to reset a code, then it's important to get it fixed. It just buys you more time and you don't have to stress about not making delivery, plus you can drive to any shop you want rather than whichever one is nearby before you get derated.

 

More than likely it’s a bad inlet and/or outlet nox sensor. Detroit aren’t terrible on price, about $225-$250 each. When it comes to sensors, only buy oem.

 

Well, first pass analysis and troubleshooting came up with this.

The injectors which push DEF into the exhaust system are apparently okay, but there is something of a design flaw with the direction that the injectors push the DEF. Supposedly this doesn't impact all DD15 engine DEF systems, but it does impact a lot of them. Essentially I have a DEF crystal buildup around the injectors that is causing issues. There is an 'apron' assembly that can be placed next to the injector to help the DEF and exhaust mix properly and prevent DEF crystal buildup.

I spoke to the home terminal shop, and they verified that this apron insert process was a common thing for 2016 Freightliners with dd15 engines. Not all trucks needed the DEF injector apron assembly, but a lot did. Mine never got one as a company truck.

I am still not entirely convinced that this is going to address the problem I want fixed, but it will apparently fix at least one problem that may or may not be related. I have driven the same sorts of patterns and mileage in this truck for over 500k miles now, and this issue is new.

So, they are doing the work, and then I'll take her out on the road and see what happens next 34.