DPF warning light came on briefly then went out. 407 HDi 208

[UNM]

For the first time since I got this car five months back, the DPF warning symbol appeared on the dash.
It did this toward sthe end of a 250km drive, having driven at 100km/hr most of the way, including a portion in 5th gear (auto) to try an dclean the filter out. It only came on for a few seconds then went out. No further problems and I then drove the same distance back to Melbourne the next day.
A check with the diag tester suggested a load of about 23% in the filter.


Question:
When the warning symbol appears, would it be expected to stay on until the filter was regenerated?
Anyone know what causes it to come on? Is it based on pressure differential between upstream/downstream sensors?

TIA

 

[N5GTi6]

23% does seem like quite a high blockage - from memory our 220K km's RHR 308 was about 4% blocked. Sounds like you need a few regular Sunday drives...

Cheers

Justin

 

[seasink]

There are pressure sensors for the DPF at the rear of the engine, with tubes coming from the filter. I have often had the warning on a motorway, and have just kept driving. It sorts itself. A steady speed for a while is all the computer wants when the pressure signal comes. There is no need for engine revving or low gears. The aim is for the regen to occur on an open road where no person or another vehicle can be harmed by the exhaust.

 

[UNM]

23% does seem like quite a high blockage - from memory our 220K km's RHR 308 was about 4% blocked. Sounds like you need a few regular Sunday drives...

23% is as low as I have had it. It was at 100.1% the week before. (this is the number from DATA list 13 incidentally).

I am not sure what exactly data list 13 and data list 15 are actually telling me as they seem wildly different.

There are pressure sensors for the DPF at the rear of the engine, with tubes coming from the filter. I have often had the warning on a motorway, and have just kept driving. It sorts itself. A steady speed for a while is all the computer wants when the pressure signal comes. There is no need for engine revving or low gears. The aim is for the regen to occur on an open road where no person or another vehicle can be harmed by the exhaust.

As luck would have it. the symbol appeared with 5km to go on twisty hilly roads, followed by a 2km section of 10km/hr to my destination. Light still went out quickly and didnt come back on again which surprised me.

I was under the impression that for a successful regen, it would need to keep engine revs above 2000 or so.