On a recent drive with an OBD-II scanner plugged in, I noticed the soot weight in the DPF as reported by the ECU started at 0 grams, steadily rose to around 600 grams, dropped back to zero, and slowly rose up to 600 again. This was over the course of about 30 miles.

(I had previously assumed the soot weight was estimated from the differential pressure across the DPF, but that is measuring as normal. The DPF has recently been taken off the car and manually cleaned of ash and the DPF sensor is new. I also believe 600 grams is a wildly unrealistic number for soot in the DPF?)

Even stranger, the reported distance since last DPF regeneration rises much faster than the distance I travel. Over the same 30 mile journey, this number rose from 2000 km to 4000 km, then dropped to 0 (whether because a regen had happened or more ECU weirdness, I don't know) and then started to rise again to around 1000 km.

Is it possible the soot weight estimate is also based on distance since last regen, so one of them being wrong is throwing out the other? Is this likely to be an ECU problem? Or is there another sensor that could be broken and causing this?

Edited by Andrewww on 19/07/2023 at 09:44