After I got this warning, I decided to see if it could be fixed without having to disassemble the particle filter, or to switch it with a new one. I loaded up DIS, and found 3 errors in the DDE module.
4010 : Exhaust backpressure sensor (this will show up as P14A1, if you use a standard OBDII tool)
480A : Particle Filter clogged (Exhaust Back-Presure high)
481A : Particle filter clogged (Exhaust Back-Presure above maximum)
I had not noticed any issues with my car, it ran as it should, just had the Particle Filter Warning come on sporadically. It could be 3 days, or it could be 30 seconds after startup. There was no pattern.
I then decided to force a Particle Filter Regeneration, but that would not run.
This led me to believe that the particle filter was not as clogged as 480A/481A suggested, and since the 4010 error was present, it was easy to determine that the generation would not run if the DDE cannot rely on the backpressure sensor..
Makes a lot of sense..
The sensor measured 1001mbar pressure with the engine off, this had to be wrong, since it is way way way above maximum.
I ordered a new sensor (Part number : 13627805152), costs only about 50 Euro, and since my local dealer had them on stock, I also concluded that they are normal to go defect.
It took 5 minutes to change it, the sensor is a clip-on sensor at the left back side of the engie. You only need to just take the engine cover off, this takes 3 seconds since it is also clipped on.
Then remove the connector, and the vacuum tube, it is insulated by the silver heating stuff, just clip off the green wire strip, and pull off the vacuum tube.
Then just slide the sensor towards the front off the engine and replace with the new one. Very very easy.
After the change, the pressure was now 0 mbar with engine off, much more what I expected :)
Cleared all 3 codes, requested a regeneration in DDE, and went for a 80km drive on the highway. The regeneration started almost immediately after engine had reached working temp (85 degrees), and the regeneration kept on going for almost 70 kilometers.
A lot of smoke coming fra the exhaus in the beginning, but that cleared up quickly. Exhaust temperature was above 600 degrees the whole time.
Unfortunatelly my images of the exhaust pressure value with the new sensor in running mode, got lost, but it was too high, so the filter needed a regeneration badly...
It is now at 28mbar at 80km/h.
Now the regeneration is running as it should, and no more warnings.
So, it you have this warning, then before doing anything else, check for the Exhaust Pressure error, and change the sensor.
If you don't have access to BMW DIS, then using a standard OBDII tool is also an option, just check for P14A1 error, change sensor, clear errors and for for a long run. Unless your particle filter really is totally blocked, then the engine will run the regeneration ASAP by itself.
According to some sites and people, the fueltank needs to be at least half full before the regeneration will take place. I haven't tested this yet, but to be sure, just fill up your tank before going for a long run :)