Diesel Particulate Filters

Hi all,

Thanks to the European bureaucrats our dirty diesels are a little less dirty. No longer do we fill the atmosphere with particles ruining the lungs of children, the elderly and everyone in-between.

There's plenty of threads on the web regarding DPFs, but looking through it appears as though I should be doing everything correct.

I've had my 2016 Polo TDi for a few months and racked up 3k miles on it so it must have have a few regens during this period. Passive, mostly I hope.

My commute to work varies depending on the route I take. Usually it's 10miles of back roads followed by 10miles of dual carriageway "A" road where I cruise at a sensible 55mph. There's a 3mile up hill too...

My other route takes me down the M4 and "A" roads and is 23miles of fast roads where I sit at 55mph with the HGVs or whizz by at 70mph.

As far as I understand, these conditions (even at 55mph) should be adequate to keep the DPF in ship shape. 

Yet I've noticed on occasion when stopping at traffic lights the engine fans are whirring away noisily and the start stop does cut the engine. Idle is also around 1k rpm. Is this an indication of an active DPF regen?

It's happened 2 days in a row even with cruise control set to 70mph.

Any advice welcome,

Cheers