My 2002 F-150 5.4L V8 Check Engine light is on and displaying P0406 code. Completely new territory for me, so checked on-line and found one source that advises checking the EGR Vacuum Regulator, EGR Valve and DPFE Sensor.

I replaced the DPFE with a non-Motorcraft part one week ago when I broke off one of the plastic inlets fiddling with a COP. Could it possibly have gone bad already?

Also read that a vacuum leak might be the culprit. Any advice on how to approach this P0406 troubleshooting process is much appreciated.

 

http://www.obd-codes.com/p0406

 

It may have been bad to start with or you have a connector problem.

 

Let's see...

Whenever chasing a code, imagine there is no code.

Is the Truck doing anything else like surging or a high idle? a bad COP will give you a stumble... If you Rev it in park does it come back down to idle really slow?

If it's not doing that then I'd check the connections to the DPFE with a multimeter (if you have one) in case the connector went bad (you can cut a new one in pretty easy) and I'd check if a vacuum hose got cracked while you where in there.

But DPFE's tend to be buggy, so I wouldn't be too amazed if you got a bum one. Who was the source of the part? I've been sent bad MAF's, etc. from online stores.

Hope this helps

 

Actually, the truck runs pretty good, it's just that damned P0406 code popping up! The DPFE I bagged on Ebay from Car Parts Wholesale. No surging to report. I'll check the DPFE hoses and vacuum line to see if I can spot anything.

 

Motorcraft DPFE can be bought online for about 60 bucks, what did you pay for the one you got? Aftermarket plastic DPFE's have a history of being no good.

By the way, I'll buy from rockauto.com or Amazon long before I'll buy anything on Fleabay.

 

Noted, glc! Yeah, not knowing any better, I bagged an aftermarket one for, ahem, 35 bucks...Guess I got what I paid for! On my way to Amazon... Thanks, man. BTW, I just did a vacuum test on my ERG valve and it both held vacuum and started to stall out the engine when vacuum was applied, so I'm assuming it's OK and the throttle body ERG ports are clear as well...

 

Had the same problem on mine throttle body was plugged solid. But everything tested good. I went to a junk yard got a used one cleaned it all up swapped them an then cleaned the original have a spare now only cost me $35.00

 

Tom1969, you did the EGR valve vacuum test and your throttle body was still plugged solid?

 

If he had a plugged up throttle body, he would have gotten a different fault code (P0401), not a P0406.

Another example of misplaced enthusiasm in trying to be helpful from a new arrival.

 

I did get DTC P0406 and the throttle body EGR ports were plugged solid. Also your comment Another example of misplaced enthusiasm in trying to be helpful from a new arrival is uncalled for. I was only sharing the problem I had. Also I have been a Certififed Technician for over 20 years and currently Shop Foreman for the lst 5 years. So I do have a clue. Thanks and have a wonderful day