The soot that plugs up a DPF is carbon, which when burnt turns to CO2, there is no ash left behind unless it's poisoned by something else (like oil additives if your engine is burning oil).

That's not what I've heard...

As with any filter (think of the bag in your vacuum cleaner) they have to be emptied regularly to maintain performance. For a DPF this process is called 'regeneration' – the collected soot is burnt off at high temperature to leave only a tiny ash residue.

I also believed the same as above. Not to mention, the oil must have an impact somehow, because VW say you need to use a low ash oil.

The ash is from impurities and pollutants, not the carbon. If you've got an engine with other issues (say oil consumption) then you'll get much shorter DPF life.

Physically removing the DPF is only half the job. The other half is mapping it out of the ECU. This is the part the average garage can't do.

Edited 20 May, 201214 yr by Kiwibacon

But then if an engine was running as it should then the DPF would never need replacing?

But then if an engine was running as it should then the DPF would never need replacing?

That's right. If it always runs in ideal conditions the DPF will last the life of the car.

As your use gets further and further from ideal (short trips etc) the DPF life reduces.

As well as the ash problem, if a DPF gets too clogged up with soot, it can't be burnt clean and will need replaced.

Since when has anything always ran ideal

Since when has anything always ran ideal

Life isn't ideal, I didn't say it was.