Working on P0401 on 96 5.0

[Corrie06]

I've been searching this forum for a few days looking for information on the P0401 insufficient EGR flow code my '96 Limited 5.0L AWD has. I've found a lot of good information but not enough to fix my problem. So far I've learned the common problems are:

- P0401 is most likely DPFE sensor problem
- Could be caused by broken/loose EGR tube

I've located my EGR valve and solenoid but I don't think my engine has a DPFE sensor or tube coming from exhaust to EGR valve. I've inspected the hose going from the solenoid to the valve and it's clean. I will use a vacuum tester on the valve tonight, but almost everything I've read on this forum says the valve is the least likely of the system to fail, so can you help me out with some other things to look at and troubleshoot before I start digging in tonight?

I know basically what the EGR system is and how it works but I've never had the opertunity to troubleshoot one before. Any help about my specifric application is greatly appreciated.

 

[Corrie06]

I did the vacuum test and as far as I can tell the EGR valve is good. I started the Explorer up, pulled 5 in Hg and the engine started running rough. I ran it for a minute or two and the vacuum held.

I noticed the EGR valve has an electrical connector on it. There are three wires--brown, gray and orange. What is this and should I test it? How?

 

[jlsparky7]

Have you tried running seafoam through it a couple times? Usually that can clear up egr and misfire problems if they are carbon related.

As for testing electronics your best bet is to get a haynes manual. It has all the numbers in it.

 

[Corrie06]

I gave the Explorer the complete Seafoam treatment (intake, crankcase, fuel tank) when I got it this past spring.

I also have a DTC for the first O2 sensor on bank 2. I haven't fix it yet because I know what the problem is and I am holding on it until I figure out the EGR problem so I can buy all of the parts at once. Any chance fixing the O2 sensor will help the EGR problem?

 

[GeorgeR]

Your 5.0

doesn't have an dpfe, nor does it have an egr tube.
What it does have is a egr position sensor mounted on the egr valve which is what the wiring connector is attached to. This is what usually craps out first. If you can remove the sensor and replace it you may have solved the problem. There is also a short vacuum line running from the egr valve to another (I can't remember what) device. There is only one vacuum line coming off the egr valve. If this line is split or crumbly it will cause the same problem.(I could feel mine crumbling but couldn't see it) The really bad news is that it may be impossible to replace the sensor without taking the egr valve loose.
(ask me how I know) the egr valve cost is $100.00 or so,and the sensor is $30+/-. It sounds like your egr is ok so if you have to take it loose from the housilng just clean it put on the new sensor and you should be good to go.

 

[Corrie06]

GeorgeR, the device you can't remember is the solenoid. The line between it and the valve is in good shape. I didn't realize the sensor could be seperated from the valve, nor did I know you could buy the sensor seperate from the valve. I'll pull the valve off and see if I can remove the sensor. I'll let you know how it goes.

 

[Corrie06]

I replaced the EGR valve sensor but now I have a DTC for EGR flow exsessive! Is it posible to overtighten the nuts on the sensor and cause it to "think" the valve is open when it's really not?