[rost7]

Time to time I discover a smell of burning on the back of my X3 2.0D. The smell similar to burned rubber or isolation. It happens every week (250-300 km) and I don't see any reason of it or connection with any external factor. Most of the time I use car to drive home-office-home (30-35 km per day) with average speed 50-80 km/h. I asked authrized service to find a what could be this issue two times but they didn't find any reason of this smell. Is there anybody who had similar issue?

[VikingOne]

Are you sure its not the DPF regeneration:

To maintain performance a DPF has to be emptied regularly. This is usually done passively in a process called 'regeneration': when the exhaust temperature's high enough, on motorways or fast A-roads. The collected soot is burnt off, leaving only a tiny ash residue. This can give off a smell during the process.

https://www.youtube.com/watch?v=aMKpo74P6SE

[F30ed]

Look under the car. A plastic bag may stick to the tail pipe....

[Peter_R]

I agree with the first answer. I used to get the smell regularly many years go on my 2007 e91 325d. It was every 250 to 300 miles often after many short journeys when the dpf would regenerate.

I am surprised your BMW Service agent did not point out this possibility.

There is also the unlikely possibility that there is a crack in the exhaust system around the diesel particulate filter (dpf) allowing some gases to escape before going through the dpf. Again the service agent should be able to advise after inspection.

[rost7]

Originally Posted by VikingOne

Are you sure its not the DPF regeneration:
...

Thank you for useful reply, that video is the best explanation of DPF.

I got smell a first time in two weeks after purchasing a brand new car. When I arrived to the service (same day) the smell is gone already. I asked about DPF (there few lines about DPF in User Manual) but service guys said that must not be DPF because regeneration never happen on a brand new car and I should run at least few K of km to meet regeneration first time. But seems they wrong because according to your link there is a Spontaneous regeneration which could happen reguallry.

[rost7]

Originally Posted by F30ed

Look under the car. A plastic bag may stick to the tail pipe....

I can't happen every time

[rost7]

Originally Posted by Peter_R

I agree with the first answer. I used to get the smell regularly many years go on my 2007 e91 325d. It was every 250 to 300 miles often after many short journeys when the dpf would regenerate.

I am surprised your BMW Service agent did not point out this possibility.

There is also the unlikely possibility that there is a crack in the exhaust system around the diesel particulate filter (dpf) allowing some gases to escape before going through the dpf. Again the service agent should be able to advise after inspection.

They checked the exhoust system but didn't fine anything. It was strange to me why they didn't perfom a computer check, it could show if it was DPF regeneration.
I have bought Carly App with adapter, gona check by myself.

[rost7]

I have checked the car by Carly App. It shows 31 DPF regenerations was successfully passed. It is around 300 km between regenerations. It looks like nothing to worry about. Thank you all to your replyes.