Because the DPF is under the car, not 'close coupled' in the exhaust manifold, the car needs to be driven quite a long way (50 miles) at 2000 - 2500 rpm to get the DPF hot enough to promote a passive regeneration. An active regeneration will happen automatically, but if the DPF is too stuffed up with soot for this to work, the post-injected
BMW states in DIS57 that the DPF regen requires; 10 litres of Diesel in tank Coolant temp to be over 75c Constant 40mph road speed Most DPF regen issues are caused by faulty coolant thermostats and constant short journeys, both resulting in engine temperatures not going over 75c, so the regen process does not happen resulting in a heavily clogged DPF. . 265 324 310 33 150 75 306 63 294