a blocked DPF can generally point to issues towards your vehicle’s Exhaust Gas Recirculation (EGR) valve as well.
The EGR system is responsible for redirecting a small amount of exhaust gases back into the engine intake manifold in order to lower combustion temperature. An EGR valve becomes clogged or stuck close when carbon build up on the valve causes it to stick.
When an EGR valve becomes clogged or stuck close, it can increase the amount of diesel soot passed on to the DPF, contributing towards faster blockage. A clogged EGR valve alone can cause a rough idle and heavy knocking, both of which are tell-tale signs of pre-detonation.