Why is the rum gone?
Join Date: May 2012
Location: United Kingdom
County: Greater Manchester
If it struggles from low revs then it's probably the EGR,
Blank it off (and either live with the warning light or get a dongle (or a remap))
The DPF regens don't have any warning light, you will notice them as the fuel consumption will go through the roof and when you take your foot off the throttle the turbo boost needle will drop very quickly to nothing.
Regens usually take about ten mins and will normally happen on the motorway or a long dual carriageway trip, you can stop them when they start (if you come to the end of your journey just switch off as normal) and the regen will start again next time you meet the regen criterion (constant high speed for a period of time, engine up to temp, whatever the criterion are!)
also they tend to happen around every 600miles or so, it's controlled by a countup timer from 0 to 100% in the ecu, but it doesn't always reset to 0% after a regen, that is partially controlled by the pressure sensor in the exhaust. so if your DPF is really badly blocked a regen might not reduce the blockage enough to run at optimal, so the counter only resets to 30%, then it counts up to 100% on the timer and regens around 100% (if it can, again this is down to temp, speed etc etc) so effectively regening early. If this regen clears more of the blockage than the last one the counter might get reset to 10% which will give you a little longer before the next regen.
There are lots of threads on here and other sites telling you that when you notice a regen happening drop down a gear or two to increase the revs, this is wrong, drive normally in whatever gear is right for the conditions, if you are sat on a clear motorway at 70mph when a regen starts and you drop down into 4th or 5th the gas flow through the DPF increases and this cools the DPF (with a regen the hotter the better) if you stay in 6th the unburnt fuel will sit in the DPF for longer and burn off the soot more effectively, if you have an ODB2 adaptor and Multi ECU scan on a laptop you can watch the DPF temperature and lower gears generate lower temperatures.
Hope this made sense.