E71 X6M 50D DPF problem

[Erudito1312]

Hi, recently got a problem with DPF, was hoping maybe someone has an advice.

I got a DPF error on my display, and since I drive very short distance - not that much of a surprise. However what is weird is that in Summer I had a drive of over 300KM, and for some reason it still did not regenerate...

Anyways, I hooked up car diagnostics (dont have ISTA sadly, only default Delphi), put my wife on passenger seat, and went on a highway. We drove for over an hour with a constant speed of 90 km/h, and all the time she was erasing the 480A and 481A fault codes. The thing we noticed with the computer is that regeneration usually would start for barely 10 secs, then turn off and give the error. We tried forcing the regen manually via Delphi, but at first it did not work.

After almost an hour drive with no stops/slowing down regeneration started turning on for 40-60 sec, and in the end the 481A error disappeared, however 480A still comes up no matter how many times we erase it. Also, Regeneration is not changing to "in progress" anymore, not even for those 10 sec as before, not even after removing the code and manually turning on the regeneration process.

Exhaust back pressure is 14.9 mbar on idle (which I thought was not high according to some messages on similar topics ive seen), and the weird part also was that we were checking the exhaust temperature (I read it should be quite high), and the way it was working with those 10 sec "regeneration in progress" interwals is that temperature would be around 350+C, then it would raise to 500, but as soon as it goes up there - regeneration turned off and temp would fall back to initial 350+...

I have a feeling that it has to be some sensor issue, but there are no other fault codes in Delphi. Any ideas/advice appreciated!

Cars milage is 125,000 KM.

[conandrum]

I also would like to know.
If you have made any discoveries since the last post, let us know.

[conandrum]

check out my own thread here:
https://www.xbimmers.com/forums/show....php?t=2165908

[Conwonthedon187]

if your scr is bad it's not going to get super hot like it should, because the catalyst isn't reacting to the urea and causing the chemical reaction to conver the nox gases to nitrogen and h20. At least that's my understanding of the SCR/DPF.

[Conwonthedon187]

also like in the other forums if your thermostat isn't closing and stuck open/malfunctioning the engine wont be hot enough for the computer to command a regen.

[Erudito1312]

Forgot to update here in case someone in the future will find the thread with same problem. So, no idea what happened, but after driving for quite some time it finally was regenerating for like 3-5 min. The error is gone and did not come back again. Tried to run the cleaning again manually but it did not do anything.
Had the car at my mechanic who spent some time on it, and his verdict was that DPF is ok, there is no issue that he found and no excessive dirt. Diagnostics does not show any errors, and its been almost a year since with nothing on my display (did not connect laptop anymore though). So there is that, weird bug or for some reason car needed even more time for me to drive to finally start the regen, idk.

[stefanello_cs]

The general design of the X6 diesel engines (30D, 40D and 50D types) is for long distance usage when DPF regeneration is executed when necessary with success because the engine has the time to reach the necessary parameters to start and successfully complete DPF regeneration.
So, if you understand and keep in mind how the DPF regeneration works then when you know you're driving for short distances and short period of times - for instance city driving for 5-10 km to office and return back home monthly - then even if the car computer will try to execute DPF regeneration then it will not finish successfully and after a specific number of tries (I don't know exactly this number) then the DPF error will be permanently stored until either the error will be deleted (ex. with a tester) or if the DPF regeneration will be executed successfully.
Keep in mind that:
1. only deleting the error will only temporarily get rid of the error, as after again unsuccessfully executing the regeneration for a number of trees the error will be back stored. So, the correct procedure is in the end to execute the regeneration successfully
2. to enforce the DPF regeneration - when it is necessary to be executed - you must drive the car with a constant sped of 80 km/h or more and 2200 rpm or more for approx. 15 minutes - you'll find the right speed/rpm/time values by experiment on your own. To do so, drive in sport mode or a better option is manual mode (when you change the speeds either from the steering wheel pads or from gear shifter stick and you are able to maintain the engine rpm and car speed as you desire). Up-heel driving will speed up a lot the regeneration time as the engine works harder. Also, if and when you have the stored error then enforcing DPF regeneration this way will automatically clear the error as well.
3. it is possible that enforcing the DPF regeneration will not work no matter how high RPM and speed is. This generally means that there are some other errors somewhere in the engine: either some DPF sensors are failing - there are 3 sensors related to DPF, reading oxigen and exhaust gas mixture - either some other intake sensors that when failing the DPF regeneration will not be able to start at all. In this case, if you tried the procedure from 2nd point 2-3-4 times and regeneration is not started and error is still present then you must not force to regenerated as more harm can be done. A diagnose must be executed and fix first the other problems that prevent the start of DPF regeneration

So, if you drive most of the time for short distances then to avoid any problems and protect DPF the general advice is to drive once a month your car in the way DPF regeneration is executed as described at 2nd point above.