Two weeks ago I got 2 CEL codes pulled. P0401(EGR Flow Insufficient) and P0402(EGR Flow Excessive). So, over the weekend I cleaned out the EGR passages, reset the computer, and all was good, I thought. Yesterday, I get another CEL, the P0402(excessive) again. So I am thinking it may be the EGR Valve or the DPFE sensor I heard someone say it may be.

I would like to know which of these or something else would most likely be causing the CEL.

Also what is the DPFE Sensor?? Is that the same as the EGR valve pressure sensor?

Both the valve and pressure sensor are available at autozone. Are these hard to replace? And also where are these located.

Thanks in advance.

98 Black Mystique LS Duratec V6 2.5L ATX K&N air filter, cleaned EGR, new Autolite double platinum plugs, magnacore wires, rebuit Sonnax valved VB, TSS, TPS. Mobil 1 5W-30