As described in the 300 Series handbook #####, there is an option to have the DPF button reprogrammed by your dealer to be set to "Custom Mode" Or "Mode 2". Our dealer didn't charge for this change. This allows you to do a DPF burn on demand rather than waiting for it to be 50% full. One advantage would be if you know your heading into long grass and don't want the DPF to do an automatic burn, without your control, you could initiate a manual burn in a suitable safe location.
When programmed to Custom Mode, the DPF will offer you a manual burn when the PDF soot level is 10% or more. A message is displayed on the dash on startup for about 2 seconds. (12" Screen, from GR, shown below)
At this point there are two options:
Dismiss the message with the "U Turn button" or wait for the 3 secs - nothing happens and the DPF will do an auto burn as normal when needed.
Press the DPF button again and the DPF will initiate a burn. If you are stationary and in 'P' you will get this message below. Note the warning. Engine speed will rise to around 2000 RPM. I haven't measured the time taken to do a burn under these conditions.
If you drive off at this point, the DPF burn will stop but will be re initiated a soon as the normal DPF burn conditions are suitable, eg engine temp etc. This will continue across engine restarts ie once you have initiated a manual burn it will continue trying until it completes.
Hope this helps