ok. i own a 2001 ford ranger v6 4.0l SOHC. my CEL comes on. code is p0401. EGR FLOW INSUFFICIENT. ok replaced the dpfe sensor like my mechanic said. worked!....for 6 months. same code... ok must be the EGR valve itself. got a new one. works great... 5 months later same thing... replaced sensor.. AGAIN.. i am currently on the same problem 3 years later with a new EGR valve. going on 5 DPFE sensors. and the same code every 4 to 6 months. truck has no running problems AT ALL. just the $%#@@#% CEL. any ideas? note: light goes on once. once the sensor is changed. stays off for a long period.

 

Get a FoMoCo DPFE sensor, check the lines