Dpf data questions


Veteran Member
Feb 8, 2012
Orange County NY
03 Jetta Wagon Tdi, 2010 Golf TDI
Hey all,
Been noticing mpg going down and looked at the dog data today and oil ash vol is reading 180 and soot load calculated is 15. Is the oil ash number the one that tell me how full it is? Not sure what limits are but thought closer to the 300 was when it was full but I'm not sure.

Thank you for the help


Top Post Dawg
Apr 18, 2009
Fairfax county VA
2009 Jetta wagon DSG 08/08 205k buyback 1/8/18; replaced with 2017 Golf Wagon 4mo 1.8l CXBB

may be of interest.

and page 69 of http://www.natef.org/NATEF/media/NATEFMedia/VW Files/2-0-TDI-SSP.pdf

The calculated soot should increase until an active regeneration event, while the measured soot will vary up and down depending on passive regeneration while driving (like steady highway drives). if enough miles have passed, the ECU will start an active dpf regeneration regardless of the soot level estimates.

the ash is a calculated measure, and I have not seen any actual measures to validate the readings. like you, I have seen folks with ash levels closer to 300, and at least one professional mechanic has never had to change or clean a DPF for ash loading. No one has identified a hard limit for ash loading.

might be good to log some activity, and validate if the reduced mpg is from frequent regenerations

would be good to watch the dpf differential pressure, which is also used with the mass flow sensor to calculate measured soot.