Hi all. Can someone confirm that my Focus 1.6tdci 2010 has a dpf? Also how do you check any levels of fluid etc. I can see the cat in the front and there are 2 blue sensors and what looks like the 02 sensor. How the heck does the system work? Any help would be greatly appreciated. Thanks 

Yes it has a DPF.  The blue temp sensors indicate that it is a coated DPF, so no fluid.  (Changeover from fluid DPF to cDPF was around 2009).  It is a completely non serviceable part that should last the life of the car.

Works very simply.  The DPF core is a porous brick that allows gas to pass but catches soot particles.  Every 500 miles or so, the DPF pressure sensor detects soot levels are reaching the regeneration trigger point.  When regen is triggered, post-injection is used to inject diesel after combustion.  This diesel flows into the exhaust and ignites when it hits the hot cat.  That small amount of fire then ignites the soot in the DPF.  Soot is burnt into less harmful gas which flows through the DPF core, and leaves just a tiny amount of ash residue in the filter.  After around 150-200k miles, that ash residue is too great for the cDPF to continue working effectively.  It then needs to be dismantled and sonically cleaned as there is no way to make ash small enough to pass through the DPF core.

Your Euro 5 spec DPF has an O2 sensor for tighter NOx regulation via the EGR and air doser (throttle body).

Thank you very much. That would explain everything. 

Thanks again