DTC P0401?
Junior User
Joined: Mar 2011
Posts: 57
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A better look...
Checking voltage...
I hope I'm doing this right... highest voltage I got was 0.24V, and it dropped off after that, so my guess is I need to replace the DPFE sensor. Is the voltage supposed to remain steady, or does it normally drop off after turning the key?
Checking voltage...
I hope I'm doing this right... highest voltage I got was 0.24V, and it dropped off after that, so my guess is I need to replace the DPFE sensor. Is the voltage supposed to remain steady, or does it normally drop off after turning the key?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
The output should remain steady at KOEO, according to the info at the link I sent you. Thoroughly inspect those silicone hoses leading to/from the DPFE and the EGR tube. They are a trouble spot.
I love the photos, BTW! Nice work.
I love the photos, BTW! Nice work.
Junior User
Joined: Mar 2011
Posts: 57
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BTW, thanks, I'm glad you like the pics! 
It's helping me also, so I can remember what I did when it comes time to put it back together. This is already way beyond what I would normally take on myself, but after dropping $400+ on a new brake line, I'm relucant to spend much more on a pro job if I can DIY.
I FINALLY got those stubborn nuts off. I'm thinking this is the original factory DPFE sensor. I'm thinking I might put in a washer when I put in the replacement. Gonna pick up a Duralast plastic DPFE from the auto parts store today, about $60.
As far as I can see, the hoses look okay. It's really hard to see in there, and I'm afraid to remove them (or anything else in the way, for that matter).
Any tips on how I can inspect more thoroughly?
It's helping me also, so I can remember what I did when it comes time to put it back together. This is already way beyond what I would normally take on myself, but after dropping $400+ on a new brake line, I'm relucant to spend much more on a pro job if I can DIY. I FINALLY got those stubborn nuts off. I'm thinking this is the original factory DPFE sensor. I'm thinking I might put in a washer when I put in the replacement. Gonna pick up a Duralast plastic DPFE from the auto parts store today, about $60.
As far as I can see, the hoses look okay. It's really hard to see in there, and I'm afraid to remove them (or anything else in the way, for that matter).
Any tips on how I can inspect more thoroughly?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
They are made of silicone so they should not be as brittle as those pesky vinyl vacuum hoses are. You should be able to tug on them a bit or remove them. If they break, then it was time for replacement anyway.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
That would be the ones in question. From the photos you posted it looks like there is a junction point. If that is the case you will also have to be sure the rest of the tubing that attaches to the EGR tube are in good shape.
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Junior User
Joined: Mar 2011
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You mean the vacuum lines? Not much else there that I see. The junction, from what I can gather, goes right into the EGR tube. Then there's the green vacuum line that runs from the EGR control solenoid. Not that I know what I'm talking about, but here's some pics. 
So here's what I figured was the control solenoid, looking at vacuum diagram on hood.
Followed the green line to what must be the EGR valve (pretty obvious, huh).
I'm guessing the EGR tube is this metal tubing that connects the DPFE sensor to the EGR? From this angle, you can see the silicon tube from the DPFE going into the junction you referred to from the opposite side.
I'm still not seeing any obvious signs of trouble, but that's why I'm posting pics.
Thanks for the help!
So here's what I figured was the control solenoid, looking at vacuum diagram on hood.
Followed the green line to what must be the EGR valve (pretty obvious, huh).
I'm guessing the EGR tube is this metal tubing that connects the DPFE sensor to the EGR? From this angle, you can see the silicon tube from the DPFE going into the junction you referred to from the opposite side.
I'm still not seeing any obvious signs of trouble, but that's why I'm posting pics.
Thanks for the help!
Junior User
Joined: Mar 2011
Posts: 57
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Got the new dash bulbs today and replaced all of them. Now the CEL comes on, as it should. Unfortunately, now it won't start!! 
I didn't take anything apart except for replacing the DPFE sensor and dash bulbs (yet), so what could I have done? 
I didn't take anything apart except for replacing the DPFE sensor and dash bulbs (yet), so what could I have done?
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
You mean the vacuum lines? Not much else there that I see. The junction, from what I can gather, goes right into the EGR tube. Then there's the green vacuum line that runs from the EGR control solenoid. Not that I know what I'm talking about, but here's some pics.
So here's what I figured was the control solenoid, looking at vacuum diagram on hood.
I'm guessing the EGR tube is this metal tubing that connects the DPFE sensor to the EGR? From this angle, you can see the silicon tube from the DPFE going into the junction you referred to from the opposite side.
I'm still not seeing any obvious signs of trouble, but that's why I'm posting pics. Thanks for the help!
So here's what I figured was the control solenoid, looking at vacuum diagram on hood.
I'm guessing the EGR tube is this metal tubing that connects the DPFE sensor to the EGR? From this angle, you can see the silicon tube from the DPFE going into the junction you referred to from the opposite side.
I'm still not seeing any obvious signs of trouble, but that's why I'm posting pics.
Thanks for the help!As a matter of fact that is the next area to go to...the vacuum hoses leading to the EVR and the EGR. If the EVR is not allowing vacuum to the EGR, that will trigger an EGR code.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Sometimes bad things happen. Will it not crank over, like a dead battery? Does it crank but not start? Have you checked for spark, fuel, etc.?
Junior User
Joined: Mar 2011
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It cranks but won't start. Battery may be close to dead. CEL and battery lights come on and stay on. Maybe a jump? I really am clueless. 
I'll check out those hoses next, but first I'd like to get it started! Thanks!!
I'll check out those hoses next, but first I'd like to get it started! Thanks!!
Junior User
Joined: Mar 2011
Posts: 57
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Ah-hah! This is kinda funny... I hadn't put the bezel back on yet, so the front/rear fuel tank switch wasn't connected. Well, the front tank never worked since I bought the truck, and apparently, if the switch isn't connected, it defaults to the front. So, I connected the tank switcher, set to the rear tank and voila, started right up. 