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How I Fixed Too Frequent Regen Issue

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2500Ram

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Disclaimer: this worked for me - may or may not work for you. I don't work for or get a dime from anyone to write this and do not care if you follow my lead.

My 22 Cummins had been fine until recently. Then the frequent regeneration started. Like every couple days. But nothing on my end had changed. I was running: Rotella 5w-40 and Walmart DEF. No fuel additives in a long long while.

What I did: found out that the DEF system can cause the frequent regens by crystalizing where you don't want it to. Theres an additive for DEF called BARDAHL or something similar to that. Well I didn't want to blend that in and mess anything up so I bought the Tractor Supply Premium DEF with the additive. This additive loosens up the crystalization.

I changed my oil again. Did new fuel filters and an air filter. Topped off my DEF tank with the DEF fluid that has the Bardahl. Finally added a bottle of Lucas DPF cleaner and cetane booster (this seems to be just any old cetane booster as they all help burn hotter and clean out the DPF).

My truck did 1 regen almost immediately after the above service and then the DPF gauge stayed at zero for the past many hundred miles.

I highly recommend this DEF treatment (probably can be any brand but mine is running bardahl) and a cetane booster because who knows if what were getting is hot enough (again any brand probably fine).

I am happy as a clam and my 450 mile trip today averaged 22.4MPG.

Your experience may vary but I consider this matter resolved.
 
2500Ram said:
What I did: found out that the DEF system can cause the frequent regens by crystalizing where you don't want it to. Theres an additive for DEF called BARDAHL or something similar to that. Well I didn't want to blend that in and mess anything up so I bought the Tractor Supply Premium DEF with the additive. This additive loosens up the crystalization.
Click to expand...
I'm glad your fix worked and I'm interested in how did you "found out that the DEF system can cause the frequent regens"?
 
I’m gonna go out on a limb and say the DPF cleaner was the culprit due to my experience with the archoil DPF cleaner, using it gave me and others a very similar DPF cleaning/soot loading experience. I have a hard time believing def fluid being injected into the exhaust is causing regeneration issues, it is after all just water and ammonia. I am glad you have a discovered a fix for your regeneration issues though, that can be very frustrating.
 
Crystallisation is a big concern and we always remove the DEF injector for inspection and cleaning and cleaning the hole the injector mounts to.
We also test the Adblue religiously to make sure the Adblue ratio/quality is always as close to 32.5 % as possible we reject anything under 30% Adblue is 32.5% urea and the rest demineralised water.
If the pump stops working we remove the tank and flush the tank with warm water to dissolve the crystals.
But it never ever crossed my mind it could cause frequent regen's, mainly because the vehicles I work on dont do the 24hour no matter what regen, its always by how the vehicle is used and driven the ECU works it out.
So this is something very interesting and I just want to learn more.
 
So, @2500Ram, just so you don't end up spending money on premium DEF for the rest of your life, I think it's important to realize that you're correlating issues than not be the causation. You had an issue (frequent regen) and you performed the following:
  • "Upgraded" to a premium DEF
  • Changed oil
  • New fuel filters
  • New air filter
  • Fuel additive with DPF cleaner and cetane boost
Your DEF injector is after your DPF, and regens are there to clean the DPF, the two systems work in tandem, but are not tied if that makes sense.

The DPFs job is to capture and burn off excessive fuel that forms as soot post combustion. This soot collects in the DPF primarily during low RPM driving (ie. starting from a stop around town, lugging the engine while towing, etc.). It is then burned off via regen, which is basically heating the DPF.

The DEF/SCR system on the other hand is to capture and convert NOx into basically water. While the soot loading and DPF are primarily there to treat low heat excessive soot, the DEF/SCR system are there to capture NOx during high heat.

As an example, look on youtube for videos of any deleted truck, or 5.9 Cummins. You'll see that when the truck is at a dead stop, and start to accelerate, it blows soot, however as the engine RPMs climb, and the turbo spools, it creates more efficient and complete burn, and thus that black soot clears up to nothing. That "nothing" is actually high NOx, but it's invisible to the naked eye. The purpose of the DEF/SCR system is to address that "invisible" NOx, the DPF is there to address the black soot.

If you feel highly confident that the additives in the more expensive DEF are worthwhile, by all means spend the money and continue using it. I don't see any harm except to your wallet. Most likely though, your issue was addressed by the fuel additive that cleaned out the DPF, not anything else you did.
 
AH64ID said:
Either you’re mixing terms or something else is going on. DEF has zero impact on DPF and regen frequency.
Click to expand...
Help me understand this, as it says the SCR does cause a regen.

P24AF-00-PARTICULATE MATTER SENSOR CIRCUIT PERFORMANCE

The Particulate Matter (PM) Sensor is used to determine the efficiency of the Diesel Particulate Filter (DPF) by measuring the amount of particulate matter (soot) remaining in the exhaust gas after the DPF. The PM Sensor is located at the outlet of the Selective Catalytic Reduction (SCR) Catalyst and consists of a probe and module. The probe and module cannot be serviced (or diagnosed) separately. The probe and module are serviced as one unit. The module communicates with the Powertrain Control Module (PCM) over CAN Bus communication circuits.

The probe contains three internal parts: a heater, a temperature sensor, and a set of particulate measuring electrodes with a high electrical resistance. During normal operation, the module will activate the heater and perform a regeneration of the electrodes to burn off any deposited soot before taking a measurement. After sensor regeneration is complete, soot particles from the exhaust gas are then collected onto the electrodes and form conductive paths between the electrodes leading to a drop of the electrical resistance. The decreased resistance results in an increased current across the electrodes, which is compared against calibrated thresholds to determine sensor functionality and DPF efficiency.

Before starting a new measurement, the PM Sensor will perform a regeneration of the electrodes to burn off the deposited soot so that each measurement starts at similar conditions. The regeneration is considered successful if the probe's heater is able to maintain the regeneration temperature and the PM Sensor transitions into measurement mode.
 
John Jensen said:
Help me understand this, as it says the SCR does cause a regen.

P24AF-00-PARTICULATE MATTER SENSOR CIRCUIT PERFORMANCE

The Particulate Matter (PM) Sensor is used to determine the efficiency of the Diesel Particulate Filter (DPF) by measuring the amount of particulate matter (soot) remaining in the exhaust gas after the DPF. The PM Sensor is located at the outlet of the Selective Catalytic Reduction (SCR) Catalyst and consists of a probe and module. The probe and module cannot be serviced (or diagnosed) separately. The probe and module are serviced as one unit. The module communicates with the Powertrain Control Module (PCM) over CAN Bus communication circuits.

The probe contains three internal parts: a heater, a temperature sensor, and a set of particulate measuring electrodes with a high electrical resistance. During normal operation, the module will activate the heater and perform a regeneration of the electrodes to burn off any deposited soot before taking a measurement. After sensor regeneration is complete, soot particles from the exhaust gas are then collected onto the electrodes and form conductive paths between the electrodes leading to a drop of the electrical resistance. The decreased resistance results in an increased current across the electrodes, which is compared against calibrated thresholds to determine sensor functionality and DPF efficiency.

Before starting a new measurement, the PM Sensor will perform a regeneration of the electrodes to burn off the deposited soot so that each measurement starts at similar conditions. The regeneration is considered successful if the probe's heater is able to maintain the regeneration temperature and the PM Sensor transitions into measurement mode.
Click to expand...
The PM sensor has nothing to do with the SCR or DPF regeneration. The sensor regeneration and DPF regeneration are different processes. When the PM sensor does a regeneration it heats up its electrodes enough to remove any accumulated soot before it can take a reading.
 
superjoe83 said:
The PM sensor has nothing to do with the SCR or DPF regeneration. The sensor regeneration and DPF regeneration are different processes. When the PM sensor does a regeneration it heats up its electrodes enough to remove any accumulated soot before it can take a reading.
Click to expand...
So the term regeneration in P24AF-00 is generic? That it is merely regenerating/cleaning itself so it can do its job? Got it, thanks
 
John Jensen said:
Help me understand this, as it says the SCR does cause a regen.

P24AF-00-PARTICULATE MATTER SENSOR CIRCUIT PERFORMANCE

The Particulate Matter (PM) Sensor is used to determine the efficiency of the Diesel Particulate Filter (DPF) by measuring the amount of particulate matter (soot) remaining in the exhaust gas after the DPF. The PM Sensor is located at the outlet of the Selective Catalytic Reduction (SCR) Catalyst and consists of a probe and module. The probe and module cannot be serviced (or diagnosed) separately. The probe and module are serviced as one unit. The module communicates with the Powertrain Control Module (PCM) over CAN Bus communication circuits.

The probe contains three internal parts: a heater, a temperature sensor, and a set of particulate measuring electrodes with a high electrical resistance. During normal operation, the module will activate the heater and perform a regeneration of the electrodes to burn off any deposited soot before taking a measurement. After sensor regeneration is complete, soot particles from the exhaust gas are then collected onto the electrodes and form conductive paths between the electrodes leading to a drop of the electrical resistance. The decreased resistance results in an increased current across the electrodes, which is compared against calibrated thresholds to determine sensor functionality and DPF efficiency.

Before starting a new measurement, the PM Sensor will perform a regeneration of the electrodes to burn off the deposited soot so that each measurement starts at similar conditions. The regeneration is considered successful if the probe's heater is able to maintain the regeneration temperature and the PM Sensor transitions into measurement mode.
Click to expand...

The only correlation between the PM Sensor, SCR, and DPF is that the PM sensor is located on the SCR outlet. Aside from physical location of that sensor the SCR has nothing to do with regen or soot.

The sensor itself is what’s regenerating to be able to take a reading, thou there shouldn’t be any soot at that location with a properly operating truck.
 
Is it possible that an inefficient DEF spray causes higher NOX and triggers more frequent regeneration? I don't know but I suspect someone here does.

My truck does not have a particulate matter sensor - got a recall and I will be taking it in for installation soon.

I considered that the cetane increase was the reason for my decreased regenerations but I wanted to give the whole recipe. Can't hurt the run the entire mixture of products...just a couple bucks more really. I'm happy right now and will probably cycle between these additives going forward - however I am glad I found a way to stop it. Its been over 600 miles without a regen which would have been unheard of last week.
 
2500Ram said:
Is it possible that an inefficient DEF spray causes higher NOX and triggers more frequent regeneration? I don't know but I suspect someone here does.
Click to expand...

Regeneration occurs in the DPF which is upstream of the SCR/DEF injector.

Higher NOx has no bearing on regen, which cleans the DPF of accumulated soot.
 
2500Ram said:
Is it possible that an inefficient DEF spray causes higher NOX and triggers more frequent regeneration? I don't know but I suspect someone here does.

My truck does not have a particulate matter sensor - got a recall and I will be taking it in for installation soon.

I considered that the cetane increase was the reason for my decreased regenerations but I wanted to give the whole recipe. Can't hurt the run the entire mixture of products...just a couple bucks more really. I'm happy right now and will probably cycle between these additives going forward - however I am glad I found a way to stop it. Its been over 600 miles without a regen which would have been unheard of last week.
Click to expand...
Def consumption should be 3-5% of fuel, so lets assume a basic mpg of 20 mpg. 12k a year is considered low-average in the states, which equates to 600 gal burned a year. 4% of that is 24 gal. Each def container is roughly 2.5 gal, for simple math let's call it 2.4, so 10 containers at $5 a container more than budget DEF is only $50 a year.

Is it necessary? No. is there any real harm? Also no. again, this isn't your issue, but if you want to continue have at it if it gives you peace of mind.
 
Last edited:
UglyViking said:
Def consumption should be 3-5% of fuel, so lets assume a basic mpg of 20 mpg. 12k a year is considered low-average in the states, which equates to 600 gal burned a year. 4% of that is 24 gal. Each def container is roughly 2.5 gal, for simple math let's call it 2.4, so 10 containers at $5 a container is only $50 a year.

Is it necessary? No. is there any real harm? Also no. again, this isn't your issue, but if you want to continue have at it if it gives you peace of mind.
Click to expand...

Where do you get 2.5 gal def for $5? Thanks
 
jak said:
Where do you get 2.5 gal def for $5? Thanks
Click to expand...
Should have worded that better. The $5 for 2.5 gal is the price differential between "budget" DEF and DEF with "additives", often labeled premium or such. It's just a rough idea of price difference between the two. I'll update my initial post.
 
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