Mercedes V Klasse diesel particulate filter issue

I encountered a similar issue with my old Renault Megane, though it wasn't quite the same model year. The symptoms you describe reduced power and smoke certainly point towards a potential problem with the diesel particulate filter. Think of the DPF as your car's lungs; if they get clogged, it's going to have trouble breathing. Regeneration is basically the car trying to clean those lungs. Has the car had the chance to perform regeneration? Are you doing a lot of short journeys or mostly long ones? Also, has any warning light come on related to the engine or exhaust system?

The car does mostly shorter journeys, which I understand aren't ideal for regeneration. No warning lights have appeared on the dashboard, which is odd. Is it possible the DPF is blocked even without a warning light? And if so, is DPF cleaning a viable option, or am I looking at a complete filter replacement?

It is indeed possible that the DPF is blocked even without a warning light illuminating, particularly with the type of driving you're doing. The lack of longer journeys prevents the DPF from reaching the necessary temperature for effective regeneration. In my case with the Megane, the lack of warning lights initially misled me. Regarding DPF cleaning versus filter replacement, cleaning can sometimes be a temporary solution, but its effectiveness depends on the severity of the blockage. Given the age of your Mercedes and the potential for irreversible damage to the diesel filter, it might be prudent to seek a professional diagnostic assessment. I'd suggest taking your car to a reputable workshop equipped to handle DPF issues; they can accurately diagnose the problem and advise you on the best course of action. In the end I needed a filter replacement.

I took your advice and brought the car to a workshop. Turns out the DPF was indeed defective, and they recommended a filter replacement. The eventual repair cost was 1550€. Hopefully, this sorts out the problem for good.