Hello all!

So back in the spring, JUST before it hit 120k miles, our CD threw a CEL. It was

P226D
Particulate Filter Missing / Deteriorated Substrate bank 1

Took it to the dealer and they replaced the DPF under warranty. Yay dieselgate! I should note that this came on / after an extended highway run whereas our CD typically sees a lot of local trips.

So fast forward until now. This summer my son has been using the CD to go to work. Lots of short trips, and even fewer long trips since it's no longer our primary "family" vehicle. The other day we took it downtown on a nice run to give it the old Italian tune-up. Boom, CEL illuminates. When we got home, I pulled out the iCarSoft POR3 and read the code. Same code, stored 3X. I cleated the codes, but only two cleared. One is "persistent" or something like that. But the CEL went off. Then it returned less than a week later. Same code, stored 3X. Again cleared 2/3 of the codes but one persists despite CEL being cleared.

Question: is this code reader junk that it can't completely clear the code? Second, why do you think I got this code with a brand new DPF after less than 3,000 miles? Just not liking the Italian tune up?

 

I'm the only one, eh?

 

I'm having the same thing with my 2016. Similar situation, I do shorter trips, but whenever the CEL has come on for the same code, it is during a long trip. The DPF in my car was replaced under 1 year ago (probably 7,000 miles).

First time I took it to the dealer, they said it needed a sensor. They replaced it. Second time (8 weeks ago), they said it needed a new DPF, they also said it is in on backorder until Q3 of 2025. FUN!

I think I have driven it 1200 miles since, the CEL keeps going on and off. It goes in for state inspection in two weeks. It will be interesting to see what they do.

I'm medium paranoid because I use it to tow my track car once a month. Scared I'm going to get stranded, with a trailer. My dealer does not seem to care.

 

Thanks. I will continue to keep an eye on it.

 

Hi,
I had lots of repeat 'recurring' DPF codes 2 years ago in my CD, I did lots of research and fixed it myself and the codes have not returned since.

The solution followed a long conversation with a guy who cleans/flushes DPF's for a living. He explained that most of the time flushing the dpf or replacing it wont fix the problem, the issues lie elsewhere.
Basically the dpf is designed to clog with soot, thats its sole function, then a regen burns it all off. Short journeys prevent the regens from starting or even worse the regens start but dont complete.

The guy told me the car guesses the amount of soot in the dpf, there is no way to measure it. The way it guesses is to measure airflow restrictions at the dpf via the 'Differential pressure sensor'.
There lies the problem, the airflow is already restricted before the sensor due to carbon build up in the air intake / egr system and turbo. So if you only deal with the dpf the codes will keep coming back, as you have found.

I removed some of the easily accessible pipework/ducting from the air intake and found the walls full of carbon build up. cleaned it all up with brake cleaner and not had a problem since. Messy 2 hour job but worth it.
I also did my own dpf flush and emptied a few cans of carb cleaner into the air intake ...but cleaning the intake pipes was 100% the long term solution.
This fixed my dpf straight away, not a single CEL since.

heres some before/after pics of my soot build up.





So as you see the air flow will be restricted way before the DPF due to the nature of these engines (EGR system mainly), and the dpf sensor thinks the dpf is blocked due to the reduced airflow.
Good luck, let me know if you need any more info.
mike

 

Thanks. That COULD be it, although I doubt it. I had the car serviced about 20,000 miles ago and had the shop clean those same upper intake items.

 

I've been cleaning mine once every year to 18 months. At a year-ish, it's an unpleasant job. At 18 months it's downright nasty. I just finished an ~18 month clean with probably less than 20K miles on there. So don't doubt that intake can get restricted after "only" 20K miles.

 

Ugh, just came back on again. This time I was idling for 5 minutes while parked. This is getting annoying. Will post screen shots tonight...

 

Mine has been on and off since July. Was just at the dealer today, still no idea when they may have a part. They also cannot explain why I need a second one in just over a year.

They told me to just keep driving it, which continues to freak me out since I tow often. Don't want to get stranded.

 

Mine just came up again. There is a "permanent code" shown by the scanner. Can a dealer delete this code? My new DPF is literally 2,300 miles old. Can't be that.