P1401 - I've tried everything...

[Thed]

...but the light won't turn off!!!!!!!!!!!! I replaced the DPFE sensor with a FoMoCo official part, I cleaned out the EGR tube, replaced the EGR valve, SeaFoamed the truck twice, and I replaced the vacuum solenoid. What else could there be? Could it be a vacuum line???

 

[Earl43P]

http://www.tomco-inc.com/Tech_Tips/ttt36.pdf << READ THIS!

http://www.ford-trucks.com/forums/146732-p1401-dpfe-sensor.html

Diagnostic Trouble Code (DTC) P1401 indicates that Self-Test has detected DPFE sensor circuit input above the maximum.

Possible causes:

-- DPFE SIG open.

-- DPFE SIG shorted to VREF or PWR.

-- VREF shorted to PWR.

-- SIG RTN open.

-- Damaged DPFE sensor.

-- Damaged PCM.



In your case, the first thing I would do is run a vacuum line to the egr valve port in place of the one that goes there. Suck on that new line while it is idling to see if the idle stumbles when you suck to open the valve. It may even stall. If that does not happen, you do have blocked egr ports. If that DOES happen, investigate the electrical side of the DPFE (3 wires) as detailed in the Tomco link.

 

[Thed]

Thanks man, good info. I greatly appreciate it.

 

[Bryan22]

above maximum sounds more like a wiring problem or faulty DPFE, I know you replaced it... I don't know about OBD2, but with OBD1 if a component in the EGR system isn't working the DPFE will usually throw code saying higher/lower than expected. In 100% of the problems with my truck, above max/below min was a bad DPFE. I'd be checking the voltage going to the DPFE, and make sure everything is correct. Pretty much, just start going down earl's list of possible causes.. and to start I think the reference is supposed to be right around 5 volts.

 

[killj0y]

Sounds dumb but i cleared a code like that on my truck by making sure all vacuum lines were snug on their fittings and replacing the air filter. Just my experience with the code, weird I know.

 

[BWDuty]

P1401 My Fix

I wanted to add my experience, since this code has been hounding me for quite some time. I tried all of the usual fixes first of course.. Replaced the DPFE with one from a junkyard. That didn't work, code came back as soon as I cleared it. Broke down (figuratively, this never actually rendered my truck inoperable. Even when I had the DPFE sensor completely unplugged) and bought a new DPFE sensor, and those things aren't cheap for a 2000 2.5L. I think it set me back over $70. That still didn't fix it. After doing quite a bit more research, I found that the EGR system could get clogged with carbon build-up which has been known to trigger this code. Just to be completely safe, I replaced the EGR valve itself, the EGR tube, and cleaned the ports they connect to really well with carb cleaner. Reset the code, and bam right back on.

I had already visually inspected all of the wires, but since the code itself makes me thing electrical I decided to go a bit further. I very gently tugged on the wires coming out of the harness that plugs into the DPFE sensor. One came out with absolutely no effort, and another came out fairly easily. I suppose this could explain why replacing the DPFE sensor "fixes" the problem temporarily for some people. Handling the harness when unplugging and plugging it in might give the wire just enough contact for a little while.

The parts store wanted over $30 for a new harness, so I went around at a junk yard until I found one in which I could tug all three wires fairly aggressively and they were in there really well. Unplugged the harness, cut off enough wire to splice it to my old wires, and the problem has been fixed ever since for $2. Well, at least I have a whole new EGR system now! I guess that can't be bad for mileage.

 

[Thed]

For future update, I was able to fix this by taking off the upper intake and checking the small port that the EGR valve bolts on to. Sure enough, it was clogged. I fixed that shortly after creating this thread quite a while back and forgot to update it. Haven't had the code come back up since then. Now on to P1445.....