3.0 diesel check engine light for diesel exhaust filter not regenerating

[geopilot]

My 2021 gladiator has coded twice in 3 months. It requires a dealership visit to reset from limp mode. My dealership did the hard Regen and reset it. The second time another dealership checked it, found it was a false code (DEF filter was ok) and reset the code. Both times I had filled the DEF tank from half full to full and driven 50 to 300 miles on the highway with cruising 60 mph while towing a travel trailer. My dealership has consulted with the Jeep rep and can’t find the problem. The other dealership suggested replacing the DEF pump. Has anyone had issues with this problem? Thanks.

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[DylanM]

What specific fault codes are you getting?

 

[geopilot]

Codes show as DEF Filter needs Regen and Engine control module on Code checker

 

[DylanM]

Those aren't the specific fault codes. Fault codes would be something like P2459 or P00AF.

 

[MaximusTX]

Do you have a Banks iDASH or Scangauge that monitors your soot levels or regen status? I had an issue with mine going from 3% soot level to 98% soot levels in under 20 miles and half the time it would not regen and go into limp mode. I used the follow items and since I have used them I have stayed under 50% soot levels and will continue to the use the DEF Treatment. Not sure if that is your issue but it resolved mine. I can't remember what the codes it was throwing at the time. Forced regen always fixed it though. Haven't had any issues in over a year now with it.


Rislone® 4744 DPF CLEAN™ Diesel DPF, Exhaust & Emissions System Cleaner

Rislone 4780 Diesel DEF Treatment | Prevents AdBlue/DEF Fluid Crystallization

Rislone 4784 DEF Crystal Clean™ Diesel DEF & SCR Emissions System Cleaner

 

[geopilot]

P24A4 partial filter restriction per dealer invoice. I used to get a warning onscreen to drive on highway to autoregenerate but it coded without a warning both times.

 

[DylanM]

My 2021 gladiator has coded twice in 3 months. It requires a dealership visit to reset from limp mode. My dealership did the hard Regen and reset it. The second time another dealership checked it, found it was a false code (DEF filter was ok) and reset the code. Both times I had filled the DEF tank from half full to full and driven 50 to 300 miles on the highway with cruising 60 mph while towing a travel trailer. My dealership has consulted with the Jeep rep and can’t find the problem. The other dealership suggested replacing the DEF pump. Has anyone had issues with this problem? Thanks.

P24A4 partial filter restriction per dealer invoice. I used to get a warning onscreen to drive on highway to autoregenerate but it coded without a warning both times.

So what happened to the Engine Control Module fault you mentioned earlier? Is there really only the one fault code?

It helps to understand your diesel emissions system a bit first:

The function of the DPF (diesel particulate filter) is to capture soot as it leaves the engine, preventing the old familiar black smoky diesel exhaust. The accumulated soot gets burned off at higher exhaust temps, either passively via higher engine loads, or actively through a bit of extra fuel dumped into the exhaust where it burns. This process is known as DPF regeneration. The engine PCM monitors the pressure difference between the inlet and outlet of the DPF via a sensor to determine how much restriction, ie soot load, there is in the DPF and how/when to perform a regeneration. At no point in the DPF regeneration process is diesel exhaust fluid involved.

Downstream of the DPF you have the SCR (selective catalyst reduction) which is where Nitrogen Oxides (NOx, the stuff that causes acid rain) are converted into plain Nitrogen and water. The SCR uses a reductant to help with the reaction, and that reductant is what we call DEF (diesel exhaust fluid). The amount of DEF used is in response to the amount of NOx detected in the exhaust by two NOx sensors. The SCR/DEF system's entire function is to reduce the NOx emissions present in the exhaust gasses after already passing out of the DPF.


With that in mind, your error code P24A4 indicates that the PCM believes the soot accumulation in the DPF is too high. This code is set when the PCM compares the DPF differential pressure sensor signal to the mass air flow sensor signal and that difference exceeds a calculated amount. This code has nothing to do with the DEF system, so with the information you've provided there is no logical reason to replace the DEF pump.

Actual causes for fault code P24A4 per the service manual troubleshooting procedure include a damaged or leaking exhaust system, high electrical resistance in the differential pressure sensor circuit, damage or leaks in the tubes connected to the differential pressure sensor, a faulty differential pressure sensor, or a bad DPF.

 

[geopilot]

So what happened to the Engine Control Module fault you mentioned earlier? Is there really only the one fault code?

It helps to understand your diesel emissions system a bit first:

The function of the DPF (diesel particulate filter) is to capture soot as it leaves the engine, preventing the old familiar black smoky diesel exhaust. The accumulated soot gets burned off at higher exhaust temps, either passively via higher engine loads, or actively through a bit of extra fuel dumped into the exhaust where it burns. This process is known as DPF regeneration. The engine PCM monitors the pressure difference between the inlet and outlet of the DPF via a sensor to determine how much restriction, ie soot load, there is in the DPF and how/when to perform a regeneration. At no point in the DPF regeneration process is diesel exhaust fluid involved.

Downstream of the DPF you have the SCR (selective catalyst reduction) which is where Nitrogen Oxides (NOx, the stuff that causes acid rain) are converted into plain Nitrogen and water. The SCR uses a reductant to help with the reaction, and that reductant is what we call DEF (diesel exhaust fluid). The amount of DEF used is in response to the amount of NOx detected in the exhaust by two NOx sensors. The SCR/DEF system's entire function is to reduce the NOx emissions present in the exhaust gasses after already passing out of the DPF.


With that in mind, your error code P24A4 indicates that the PCM believes the soot accumulation in the DPF is too high. This code is set when the PCM compares the DPF differential pressure sensor signal to the mass air flow sensor signal and that difference exceeds a calculated amount. This code has nothing to do with the DEF system, so with the information you've provided there is no logical reason to replace the DEF pump.

Actual causes for fault code P24A4 per the service manual troubleshooting procedure include a damaged or leaking exhaust system, high electrical resistance in the differential pressure sensor circuit, damage or leaks in the tubes connected to the differential pressure sensor, a faulty differential pressure sensor, or a bad DPF.

The first time my dealership checked all of the above and said they couldn’t find anything else wrong. They did do a software update related to the error code after a hard regen. The second time it happened everything checked out okay after the check and the software update was confirmed. The second dealership said forced regen is hard on the DEF and may cause a failure requiring replacement of the filter.

 

[MaximusTX]

The first time my dealership checked all of the above and said they couldn’t find anything else wrong. They did do a software update related to the error code after a hard regen. The second time it happened everything checked out okay after the check and the software update was confirmed. The second dealership said forced regen is hard on the DEF and may cause a failure requiring replacement of the filter.

Mine happened on a cross country trip from TX up to ID. The first time it happened I was about 20 miles outside a city when it went into Limp Mode on a saturday afternoon. I limped it back into to the local dealership who didn't have any diesel techs available but the only tech working agreed to do the forced regen. Resolved the issue, the 2nd-5th time it happened to me on this trip I put it in manual mode and drove it with the RPM around 2500-3000 rpms in 1st gear for probably 10mins or so and then it would let me shift into 2nd and did the same thing and so on up the gears until it cleared the soot. Got home I took it my local dealership and they cleared the codes (Can't remember what they were now, it's been almost 2 years) and did a full diagnostic on it and couldn't find anything wrong with it. Now I just run the cleaners I mentioned previously and haven't had any issues with it.

 

[geopilot]

Thanks for your help. I bought an Icon T10 scan tool from Harbor Freight, an annual True Fix vehicles subscription and a gate key for Stelantis. It can diagnose and fix problems, regenerate if necessary, update software, and reset codes. The tech support is really helpful.

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