Clean Diesel DPF Data Collection Thread

why not clean the DPF instead of replace...there is a company in WA that does them.

I have a hunch that the dpf ash volumes reported by VCDS are bogus. My dpf and related components were replaced on warranty because of excessive soot in the tailpipe and low EGR flow rate.

Here's the thing: VCDS reported 48 grams of ash at about 49K miles when the dpf was replaced. Even after the new dpf was installed the ash was reported as 48 grams, even with a few hundred miles of driving. If the ecu was actually measuring ash, wouldn't the reading go back to zero?

I'm going to recheck in a few thousand miles to see what happens. Maybe there is some sort of adaptation in the software, and reported values will become more plausible.

Were the values reset when it was replaced? Doesn't sound like it. Seems I recall a procedure that is supposed to be done to reset everything when replaced.

Apparently the technician did not update the ash value. I did that myself with VCDS just a few minutes ago, however. I guess my point was that if this were a measured value, it would not have to be reset.

A lot of values are calculated and not actual measured values. The sensors needed to actually measure a lot of these things would be cost prohibited and calculated values work fine for most things.

It is hard to believe that a calculated ash value would be accurate, as how would the program know what kind of oil is actually in use, how much blow-by is present and how much ash is in the fuel?

It isn't pin point accurate. It is good enough though for things to work properly and doesn't kill the design due to extreme costs of emissions sensors. People are already complaining of the cost of emissions equipment (DPF etc...). Imagine the uproar of a $2k or more sensor to tell you "exactly" how much ash is in there. Sometime good enough is good enough.

I figured it was a value calculated from the measured pressure drop across the dpf after soot is burned to the maximum extent possible. That is one of the ways soot load is estimated.

MemberName: gmcjetpilot
Model Year: 2010
Model: JSW
Tranny: DSG
Miles: 78,500
Oil Ash Volume: 78 ml
Oil Type: Castrol SLX Pro LL03 5-30W (original engine)
Oil Type: Liqui Moly Tech 4200 5-30W (507/504) (replacement engine)
Avrg. MPG: 42.2
Comments: Engine Changed at 53,000 with a 1,000 mile 2013 CJAA Jetta Sedan TDI, retained DPF, DPF miles same as car.

You guys bring up some real valid points on the calculations/measurements of the DPF system. There always seem to be some "quirky" values when someone gets work done on the DPF, EGR, etc. After my turbo failure and a lot of oil going into and out of the exhaust system, my DPF values didn't change. Numbers before and after the turbo failure remained the same. My values didn't need reset since the original DPF was still being used, but the "calculated" values had to be off after that ordeal.
Take care and stay safe my friends!

MacBuckeye said:

You guys bring up some real valid points on the calculations/measurements of the DPF system. There always seem to be some "quirky" values when someone gets work done on the DPF, EGR, etc. After my turbo failure and a lot of oil going into and out of the exhaust system, my DPF values didn't change. Numbers before and after the turbo failure remained the same. My values didn't need reset since the original DPF was still being used, but the "calculated" values had to be off after that ordeal.
Take care and stay safe my friends!

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Yes it is calculated or derived from several factors. there is no direct probe.... mileage and differential pressure are two big factors I assume ECU uses, to name two of them. The mileage is weighted by average speed, mpg? The differential pressure is obviously related to how blocked the DPF is. There are probably more inputs or factors it uses in calculated or derived ash load and oil ash load. It is like Avg MPG on MFD, pretty close but not always right. There are things that can throw it off.

If you look at the posts in this thread, divide oil ash load in ML by 1000's of miles. It is about 0.98 to 0.99ML per 1000 miles for most folks.... Low mile cars the ratio is less. However as mileage goes up the ash load averages out to about 1.0 ML/1000miles.... some do worse.... some slightly better.

MacBuckeye said:

You guys bring up some real valid points on the calculations/measurements of the DPF system. There always seem to be some "quirky" values when someone gets work done on the DPF, EGR, etc. After my turbo failure and a lot of oil going into and out of the exhaust system, my DPF values didn't change. Numbers before and after the turbo failure remained the same. My values didn't need reset since the original DPF was still being used, but the "calculated" values had to be off after that ordeal.
Take care and stay safe my friends!

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Thanks again for doing all the work for this thread over four years.

we learned an awful lot by sharing individual info, that would have been very hard to figure out on a single car

I read the 2013/2014 2.0L TDI will pass emissions after a DPF delete. Has anyone here done a DPF delete? Someone posted the ECU modification that can be made with VAGCOM.

jerryn63 said:

I read the 2013/2014 2.0L TDI will pass emissions after a DPF delete. Has anyone here done a DPF delete? Someone posted the ECU modification that can be made with VAGCOM.

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such deletes are a violation of the federal clean air act. the only way a 2013 or 2014 will pass emissions is if it is never tested for emissions, or the tester/inspector is incompetent or dishonest.

the DPF is a critical part of the emissions system in the car.

you can search for "dpf delete" for folks who have done so.

if you were to remove the DPF, (perhaps for off road racing or to export the car someplace ULSD is not available),

you would have to have the computer programs modified (a separate violation of the clean air act)

without the DOC/DPF, unburnt fuel sent to the exhaust to heat the DPF would cause trouble.

VCDS VAGCOM is not capable of such modification.

I am learning a lot here. Thanks. There are people out there on YouTube showing off their DPF delete and probably will get in legal trouble at inspection time. I don't want to dump a lot of soot in the air anyway...so I guess I need.to start putting away money now for a DPF and if I trade it in then it will be extra money down.


Thanks everyone.

Jerry,

If the DPF fills on my 2010, I plan on having mine sent out to be cleaned rather than replacement.

bobt2382 said:

Jerry,

If the DPF fills on my 2010, I plan on having mine sent out to be cleaned rather than replacement.

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X2....not a 2010 but a 2014 and maybe when that occurs to me there will be even more places doing that kind of work.

I think we're all counting on the after-market industry to pick up the slack and start providing more of these services.
Sadly, my 2009 doesn't really qualify for "remove and refurbish" without some clever cutting/splicing. Uggghhh...

NC only has safety inspections for diesels. If you have a mil light, the car will still pass.

meerschm (and all of you).... your quite welcome on all the data history. It was certainly not scientific by any means, BUT it sure is as REAL as it gets. What better than real, street level experiences. This data should be under copyright and sold to VW!

Curious what the difference is between states when it comes to emissions testing. Would it be possible for a car to pass a test in VA and PA, but not in NY or FL ?

I will try and get the newer DPF data posts updated this weekend.

btw.. my DPF delete has been great thus far. Other than the obvious (cough cough)... it's awesome. Sitting at 168K miles and hoping to pass along to daughter in 2 years.

as to passing emissions testing,

the rules vary all over the place (more strict where the air is dirtiest, and more folks drive more cars closer together)

and the skill, motivation, training, and enforcement of the inspector varies. all over the place.

I used to take my boat trailer to a guy for safety inspection who liked it better if I did not bring the trailer. and have talked with licensed inspectors who all but said they would look the other way for a diesel emissions delete, and then other inspectors who would fail my car because the strip of tint at the top of my windshield is an inch too low on the corners.


seriously, the inspections program conducted by the states is tailored not only to the state, but specific counties, and where the air tests to miss targets, that is where the enforcement tied to registration is. also random tests with referrals.

so it would be possible for me to take a car a few miles from here and have it fail, and also to take it to another inspector and have it pass.

some places make you take it to a government run site, and some to a garage that also does inspections..


and again, it is still illegal anywhere in the country to remove or modify the emissions equipment. the focus of rules is to qualify the car model as made and sold, and rely on keeping it working to control the air quality.

so I hope you do not have any trouble in the future.

My biggest fear with the DPF delete or any other illegal mod is what happens when the car is sold.

Sure you could sell it to another TDI lover who pays a few extra because it has the delete but what happens when he gives it to his/her son and they take it to CarMax and trade it.

Someone buys it.. takes it for an inspection gets busted, they track it back to you.. Can't see it ending well

wilcharl said:

My biggest fear with the DPF delete or any other illegal mod is what happens when the car is sold.

Sure you could sell it to another TDI lover who pays a few extra because it has the delete but what happens when he gives it to his/her son and they take it to CarMax and trade it.

Someone buys it.. takes it for an inspection gets busted, they track it back to you.. Can't see it ending well

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I agree completely.....but there are folks here that will tell you it is none of your business......

There are also those that will run the car until even the Kidney Foundation doesn't want it. Years back, my father-in-law decided to help me with a new muffler in my 77 Chevy Nova. The muffler and cat were one piece and sat behind the rear seat. He took it to someone in his farm town and they pulled the cat and muffler assembly and piped a cheap replacement muffler to fit. When I finally sold the car, I couldn't get it to pass the Iowa inspection and ended up selling it to a high school kid living on the Indian reservation. No federal mandates there.

wilcharl said:

My biggest fear with the DPF delete or any other illegal mod is what happens when the car is sold.

Sure you could sell it to another TDI lover who pays a few extra because it has the delete but what happens when he gives it to his/her son and they take it to CarMax and trade it.

Someone buys it.. takes it for an inspection gets busted, they track it back to you.. Can't see it ending well

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For the most part, people who buy diesels generally intend to keep them until the only person who will buy them is the breakers yard! Take a look at the last vehicle in my signature!

what is oil ash volume an how does the vcds read all these things?

It is not oil ash but ash from the regens that burn the collected diesel soot into ash. I don't think anyone has a real clear idea of what the VCDS really reads. It seems to be based on miles, regens, and other calculations that we are not aware of, or just a WAG based on the above.

"Particle Filter Oil Ash Volume" is the label on the value reported by VCDS.

lots of literature blames accumulated ash as coming mostly from engine oil which gets past the rings or valve seats, or turbo seals, (or god knows where else) enters the combustion path and is caught in the DPF.

the VCDS software accesses the value by asking the engine controller for a reply, and stating the measuring block desired. the controller responds and sends a message out via the OBD connector (with a few stops along the way)


The label is included in a file included with the VCDS software, tied to the engine controller id ,and used to make the association.

kjclow is correct that the actual source of the value (inputs, process......) is only guessed at here, since the VW engineers have not shared the specifics with any of us.