P0401 Code

[MorganMcCann]

I've got a P0401 code recently. The DPFE and EGR are both stock parts. However, upon looking at the EGR tube there is a small dent near the first bend of the tube, but it has been like that for a while because I have not done any work near that tube in months, and I have driven the truck a good deal.
So, should I look into replacing the EGR tube first, or the DPFE?

 

[RonD]

90% of the time P0401 is a failing DPFE sensor, if the stock sensor lasted over 70k miles you have done good.
3rd party DPFE sensors seem to last longer, just FYI, and they are cheaper than OEM.
Make sure the two hoses for the DPFE sensor are clear and "air tight", i.e. no leaks, the DPFE measures the pressure difference between those two hoses, if one is leaking then DPFE data to computer will be off.

The computer can adjust EGR flow thru the pipe, so a dent shouldn't be a problem, leaking or collapsed pipe would be, but not a "dent".

 

[adsm08]

The "dent" is supposed to be there. It's a product of bending the tube to it's shape.

Ron is right, the DPFE sensor is likely giving up.

The only other real test is to put vacuum to the EGR valve with the engine at idle and see if you can stall it.

 

[MorganMcCann]

The dent is into the tube about half way. It seemed like it shouldn't be there to me, but it is supposed to be there?

 

[bucko]

I can check my 2000 tonight and let you know if I have this dent you speak of in the same location. If possible, posting a picture helps.

 

[MorganMcCann]

I've been super busy, I'll try to get a picture tonight. Sadly, I don't have a garage so the lighting will not be very good.

 

[MorganMcCann]

On the picture, if you look at the hose from a different angle you can clearly tell that there is no hole, but it is just dented.

 

[MorganMcCann]

Just an update, I replaced the DPFE. The DPFE didn't fix the problem. The CEL came back on. I got a vacuum pump from Autozone, and the EGR valve held a constant vacuum with 10lbs and 15lbs, the engine wanted to stall when the EGR was placed under a vacuum. What else could the be? The EGR Vacuum solenoid? I've also heard the vacuum lines to the DPFE can become clogged.

 

[Rearanger]

I've also heard the vacuum lines to the DPFE can become clogged.

Make sure the two hoses for the DPFE sensor are clear and "air tight", i.e. no leaks, the DPFE measures the pressure difference between those two hoses,

Your answer has probably already been given.

 

[MorganMcCann]

I do believe I somehow managed to reverse the hoses. I've drove about 70 miles since flipping them, and I have had no CEL.

 

[MorganMcCann]

Drove it for about 150 miles, no CEL came back on. I'd say it is fixed.

 

[RonD]

Good work