Had a check engine light on that just would not go away. Changed the DPFE sensor, added new hoses, blew out the connections with compressed air at 150psi, checked the vacuum egr pump, and cleaned the air intake manifold. Lights re-appeared until a new DPFE sensor was installed. Complete fix was approx 55.00 for DPFE sensor, $18.00 for 2 hoses for the EGR upstream and downstream, and took it to the shop to have them clean the intake manifold ($200.00). It was 75 % clogged. Had to replace the original DPFE sensor as it was either bad, or became damaged through this process. Hope this will help diagnose your issues if you have the 5.4 L Triton V8 engine.