Date registered: Nov 2013
Vehicle: 1996 C220 2007 ML320 CDI
Mentioned: 7 Post(s)
Quoted: 343 Post(s)
If we don't assume the worse, that it's not just a quick cash grab, I think my explanation about immediate correct fuel trims is possible, but I also honestly believe that's really all there is too it. Any other claim that this is absolutely mandatory would indeed be a cash grab. So if you are time pressured, then you don't have any way around it (like you've already failed an emissions test because of a faulty injector). Otherwise, if you can drive around a little bit, in varying conditions like city and highway driving, the fuel injector will get trimmed correctly.
Of course the side effects were all good, fuel economy came back down to normal, and the DPF resumed normal regen intervals. We mostly drive long highway trips with the ML, in summer we rarely get a regen, in winter of course they are much more frequent, but that's expected.
It's interesting you bring up the air filters, but that's a totally separate issue. If you look at the air filters on the OM642, they are pathetically small, especially for a diesel engine. By the time you reach the 40k change interval, they would completely clogged, which means various engine trims would be completely messed up. In order to immediately restore power, you would have to reset the adaptations, but they would also self correct after a little bit of driving. The real solution is to half the change interval for the air filters, if you do them every 20k then you will not have this problem.