DPF burn whilst in Low Range??

[TD5-90]

Interesting. Mine has only regenerated on motorways/autoroutes on longer drives.

That makes sense, since at motorway speed most fuel per time unit is burnt, with rare to no coasting encountered. If you drive on country roads, that's different: Load and coasting are kind of balanced, enabling passive regeneration.

My weekly commute takes me either 130km autobahn, or, alternatively, 102km country roads. I use OBDlink to monitor the parameter "Normalized trigger for DPF regen":

On the autobahn, this parameter constantly and relatively quickly rises monotonically, leading to DPF burn cycles of (much) less than 500km, depending on the weight of the accelerator foot.

When I go the country route, the parameter more or less goes up much slower (less diesel burnt per time unit), and it goes down again(!) when releasing the accelerator for more than a few seconds. Most pronounced if you drive up a hill, then coast down on the other side. Net "Normalized trigger" value of going up & down is almost zero. Means: Passive regen is working in the coasting periods. I often have only 10...15% rise of the parameter for the total distance, whereas on the autobahn route it is always more than 60%.

Means: On country roads, you can have nearly 1000kms between the regens, heavy autobahn drive can give you a regen every 200km.

From the readings, I assume that the "Normalized trigger" value is based on the differential pressure measurements. Although I also monitor diff pressure, I haven't investigated further.

My Passat 240hp Alltrack principally shows the same behaviour. "Normalized trigger" isn't supported there, but instead you see the parameter "DPF regen type" toggle when accelerating and coasting.

 

[TD5-90]

I have had a burn start as I was approaching home, 2 miles out. Si I continued on a further 5 mile drive until it had finished so it didn't finish the burn parked up outside the house.

Very reasonable. Avoid interruption of a DPF burn. I do just the same when I see engine oil temp rise above the usual 90°C under moderate loads, a clear indicator that a DPF burn is in progress.

 

[DaveB]

That makes sense, since at motorway speed most fuel per time unit is burnt, with rare to no coasting encountered. If you drive on country roads, that's different: Load and coasting are kind of balanced, enabling passive regeneration.

My weekly commute takes me either 130km autobahn, or, alternatively, 102km country roads. I use OBDlink to monitor the parameter "Normalized trigger for DPF regen":

On the autobahn, this parameter constantly and relatively quickly rises monotonically, leading to DPF burn cycles of (much) less than 500km, depending on the weight of the accelerator foot.

When I go the country route, the parameter more or less goes up much slower (less diesel burnt per time unit), and it goes down again(!) when releasing the accelerator for more than a few seconds. Most pronounced if you drive up a hill, then coast down on the other side. Net "Normalized trigger" value of going up & down is almost zero. Means: Passive regen is working in the coasting periods. I often have only 10...15% rise of the parameter for the total distance, whereas on the autobahn route it is always more than 60%.

Means: On country roads, you can have nearly 1000kms between the regens, heavy autobahn drive can give you a regen every 200km.

From the readings, I assume that the "Normalized trigger" value is based on the differential pressure measurements. Although I also monitor diff pressure, I haven't investigated further.

My Passat 240hp Alltrack principally shows the same behaviour. "Normalized trigger" isn't supported there, but instead you see the the parameter "DPF regen type" toggle when accelerating and coasting.

I think it happens a lot on motorways and we don't even notice it.
When i am cruising along at 120 or so kmh there is a lot of wind, road and Spotify noise so if it was doing a dpf burn it would just be in the background.