Symptoms of bad DPF Sensor? 100% full suddenly and nothing on CTS Edge 3?

[Thorvald]

Just had this happen over the weekend heading out camping. Truck was at 40% or so DPF full on EVIC, automatic Regen started. Just a few moments later it went to 60%, 75% and then bam 100% DPF Filter full message and of course Regen stopped. Thankfully the reduced power was still more than enough to pull the trailer just had no passing speed. Truck is booked in for service but that is over a week away.

I’ve had a Koadtech bypass cable and LX Odb cable in the truck since new so figured this was a good time to buy AlphaOBD and force a Rege… Well that was $78 dollars down the drain, would not force a Regen as not all parameters were met (though I wish it was like the dealer tool that tells you which parameter was not met), I suspect the PDF full DTC code since it could not be cleared.

Next ordered CTS Edge 3 from Amazon as it has been in my basket since the truck as new as well. It arrived, connected it up and selected anything to do with DPF under basic and advanced pids. Strangely got basically zero readings when truck was running or driving, so either when DPF is truly full the sensor reads basically 0 pressure (I would assume it would read too much back pressure) or the sensor is kaput.

I’ve previously has two CEL codes for DPF sensor back at 14,000km (65,000 km ago) so I suspect it’s yet another bad DPF sensor.

Can anyone else with an Edge 3 confirm what these values “normally“ look like? @John Jensen perhaps?

Thanks
Tim

 

[Thorvald]

Just went out for a quick drive and this time laid into the throttle, the pressure reading does change a little, almost zero at idle but goes up to .10 to .20 all the way to .52 if I rev it good in the driveway, so the sensor is reading “something” just don’t know if these are normal values.

 

[Thorvald]

 

[AH64ID]

DPF pressure differential is normally that low.

What’s not normal is the 100% PR_Regen but you’re not going into regen. What code is set?

 

[Thorvald]

Code is P242F - Diesel particulate filter restriction – Ash Accumulation

Strangely enough, I also have a P2560 low coolant message again. The truck was just in for a low coolant issue where they found they had to re-tighten one of the banjo clamps on the turbo as I recall. I’ll have to dig up the paperwork. Looks like that issue may be not resolved either.

 

[Thorvald]

I also tried enabling the manual regen feature via AlphaOBD, but it gets the following error:

 

[tchur1]

Based on my loose understanding of these systems I think the loose banjo on the turbo might have something to do with your regen issues. It seems like any issues with airflow upstream from the DPF can cause these issues. Definitely worth reviewing what happened when they found a leak previously and see if you can replicate this time.

 

[AH64ID]

I also tried enabling the manual regen feature via AlphaOBD, but it gets the following error:

View attachment 61400View attachment 61401View attachment 61402

@Jimmy07 is this possible on the pickups?

 

[Jimmy07]

@Jimmy07 is this possible on the pickups?

Nobody’s successfully enabled it yet, so what he’s got showing is as far as anyone has gotten so far. Looks like it’s properly enabled, but there’s requirements that have to be met in order for the manual regen to work, such as fuel level, certain faults can’t be stored, dpf has to be at certain percentage full, etc.

I’m guessing by that message to see dealer, it’s a certain stored fault that’s inhibiting it from being available.

 

[Thorvald]

Yes the code P242F is likely preventing the manual Regen but I was at least impressed it tried.

I was speaking with my GM buddy and he indicated that all the Duramax Tow Trucks have a manual Regen option since they typically sit for hours idling, so he assumed we must have one as well (and sure enough, looks like we do).

When and if the truck gets fixed, I'll re-activate and try it again. I suspect it is like the normal manual regen that the dealer software has:

1. Truck must be running
2. Parking break applied
3. Engine up to temp
4. No DTC Codes present
5. No touching any pedals

 

[Thorvald]

I'm leaning towards what Mbarber84 indicated in another thread:

"I would check for boost leaks, even small ones, especially after all the front end work. If you’re not getting enough air to the truck it’ll run less efficiently and you’ll soot up faster."

Since I had a coolant leak and they replaced the "banjo fitting at turbo cooler feed line at engine block" it may be related to why it sooted up so quickly.

Part Number 682101855AA - Gasket Turbo Oil Drain Pipe
Qty: 2

Strangely I cannot find that part number anywhere online.

 

[Thorvald]

Just saw they also did a recall on the last visit (July 12) when they replaced the banjo fitting for campaign ZD4 19-22 MY 6.7 Diesel Exhaust... Tech cause: 68353830AC to targeted part number 57009309AA. Looks like DEF DCU (Dosing Control Unit).

 

[Thorvald]

Does anyone have the service manual procedure/section for P242F? Especially how to actually check the soot level of the DPF to determine if it is a bad sensor or truly a plugged DPF.

Also curious if Passive Regens (which as far as I know is just pure heat from driving) will still occur with a P242F code thrown or a possible full DPF?

Might help someone else in the future when they are out of warranty (like me lol).

 

[Thorvald]

Well after some serious researching I was amazed at the amount of people that use a Scan Tool to simply tell the truck that the DPF filter has been replaced (aka reset regenerative filter timers) which is apparently one of the only ways to clear the latched code P242F and allow a manual regen. However seems rather dangerous to me, if the DPF is truly full (which I doubt mine is but while under warranty forget it).

What was interesting is that the wiTECH diag tool can show "AFT Combined Soot Load" and give an estimate number of g/L. A older chassis cab Star case indicated "P242F is a latching fault and will not clear until the soot load is reduced below 8.5 g/L", now no idea if this still applies to newer trucks but makes sense how the code cannot clear. I just need to find out which PID shows this value on the Edge CTS 3.

 

[flan]

I’m not by my truck but is there a clamp before the dpf like on big rigs you can undo to check for faceplugging?

 

[Ionicbrick]

Yes the code P242F is likely preventing the manual Regen but I was at least impressed it tried.

I was speaking with my GM buddy and he indicated that all the Duramax Tow Trucks have a manual Regen option since they typically sit for hours idling, so he assumed we must have one as well (and sure enough, looks like we do).

When and if the truck gets fixed, I'll re-activate and try it again. I suspect it is like the normal manual regen that the dealer software has:

1. Truck must be running
2. Parking break applied
3. Engine up to temp
4. No DTC Codes present
5. No touching any pedals

I have a 2022 HO and was able to invoke a manual regen a few weeks ago. You’re correct on those 5 items needing to be in place for the regen to happen. There’s nothing on the EVIC that tells you anything about a regen, but Alpha says a regen is in process. You can smell it for sure, and the truck will high idle until the procedure is complete. Took my truck about 30 minutes or so.


Sent from my iPhone using Tapatalk

 

[Thorvald]

Well the truck went in Monday and got it back today (Wednesday). Here is the report:

-AFT Combined Soot Load Estimate 10 g/l.
-Erase DTCs
-Reset Regenerative Filter Timers
-Performed stationary Regen
-Soot Level at 6.0 g/l
-Performed Secondary Regen
-Soot Level at 1.0 g/l
-Found TSB 18-067-23 and PCM flash from old part number P6401032PB to P6401032PC
-Soot Level at 3.0 g/l
-18-19-04-NZ Module, Engine (ACM) - Aisin Transmission - Inspect and Reprogram

When I picked it up the display read approx. 25% DPF full and it started an Auto Regen as soon as I started driving. Thankfully it competed this time and went to zero. ***PHEW***



Connected my CTS3 back up, re-enabled Manual Regen option and will CLOSELY monitor the DPF over the life of the truck (and CTS3 logs).




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I can't find that TSB anywhere as the search engine here will not let you search for numbers like that and the NTSB has not posted it yet, so hoping to find out what it was all about.

Now that I see the tech had no issue resetting the regen timers (I assume this is the same in Alpha OBD as replacing the DPF option), I'll try this myself it it happens again and I'm stuck out somewhere.

Hopefully this helps someone else.

 

[Thorvald]

I also found out how the Manual Regen works on the Chassis cabs, so may be the same on ours with the Alpha OBD feature turned on in the EVIC:

Diesel Particulate Filter (DPF) Manual Regeneration - If Equipped On equipped chassis cabs, a manual regeneration can be enable through the instrument cluster. The manual regeneration will allow the DPF to complete a regeneration, lowering the soot level without having to drive the vehicle.

- The vehicle must be in park to access this feature,
- The fuel level must be over 12.5% full.

A message displaying the time left on the regeneration will appear on the instrument cluster, and the instrument cluster will display the soot level.

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Will have to try when I get the DPF level back up.

 

[mbarber84]

Catching up with this thread late but the P242F is the code that causes a lot of the issues. Won’t let the truck go into regeneration because it thinks the DPF is so full of ash a regeneration won’t be effective. The clearing of the regenerative filter timer is the way to get that to go away and then allow a regeneration to happen. I would be interested to see TSB 18-067-23 as well. That’s the second time I’ve had someone report that TSB but I can’t get access to it.

 

[Thorvald]

Thankfully it got posted by theStuart’s in the TSB thread:

Post in thread 'TSBs'
https://hdrams.com/forum/index.php?threads/tsbs.3028/post-276890

i just need to verify that the “DPF Replaced” feature in AlphaOBD is the same as resetting the regenerative timers.

I also wish AlphaOBD would display the Soot level in g/l like the wiTECH tool does.