Ive just found the following on a friends A4 2008 3l v6 quattro Sunday,30,December,2012,13:54:38:05185 VCDS Version: Beta 12.10.1 Data version: 20121121 5162 - Diesel Particle Filter; Differential Pressure Sensor P2453 00  - Implausible Signal MIL ON - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Status: 00000001 Fault Priority: 2 Fault Frequency: 1 Mileage: 131863 km Date: 2008.04.10 Time: 21:07:57 Now googling around suggests this sensor needs calibrating/adapting when replacing, what is the process for doing this? Ive checked the soot level and it was around 14g, but with a dodgy sensor that might not be accurate. The car doesnt seem down on power, the engine light and coil light come on shortly after resetting though. Thanks, tom. EDIT: Engine was recently replaced with a second hand unit (sucked up water), if the replacement engine had a g450 on it, would this need calibrating to the cars ecu? In effect if this happened, could putting the original sensor back on fix it?