I have a 98Expy, 4.6L that has the check engine light on. I went to Auto Zone to have the code read. P0401 insufficient flow EGR. I have taken off the EGR valve and cleaned it and also replaced the EGR position sensor. I went back to AZ and they cleared the computers memory and the light went out for about 10 days and now is back on. Same code. A mechanic at the Ford house said it could be the EGR selenoid. If so where is that located and if I replace that what else could be the problem?

Any ideas are appreciated.
Thanks

 

The solnoid (evr) is about two inches long its round. Its has a two wire connector, below that is two vacuum lines(one should be red the other is green). On couple 4.6L I have experience plugged EGR ports. To check this is to remove the green vacuum line off the EGR valve on apply vacuum to the valve with the engine running. The rpm should change, If the Rpm don't change (drop) then the ports are plugged. IF the postd are find then go the solnoid and check to see if you have vacuum on the the red vacuum line. if have vacuum there then check yourgreen vacuum line to make sure that it is not broken some where.

 

Thanks Jonmech,

I'll check that out and see what I can find

 

I finally got the chance to check it out and the rpm's drop when a vacume is applied to the egr valve. I also have vacume on the red vacume line. I inspected the vacume tubes and they look good. Any other ideas?

Paul

 

For one must "SEARCH" for the answer you seek young skywalker..............................You must leave no stone unturned in your "SEARCH" of the knowledgeble persons have put forth for your benefit on your "SEARCH"!!!!!!!!!!

 

pmurry,

I had the same problem on my 99 Expy. I replaced the EGR and the CEL came back after a few days. I posted the ongoing problem and "wmcnally" directed me to the fix...here's his reply:

"The PO401 code is "Insufficient EGR flow". I know you just replaced the EGR. So either the "new" one is defective or there is another problem. (DPFE or Vacuum)

You can test the EGR by applying vacuum to it while the engine is at idle. If the engine stumbles or dies while applying vacuum than the valve is opening and operating properly.

If the EGR checks out, the next place to go is the DPFE (differential pressure feedback sensor). It senses pressure differences between the exhaust and intake systems and "tells" the PCM to open the EGR. Sounds complicated but is easy to change. In fact on new vehicles with a PO401 code Ford tells it's techs to just change the DPFE right away, not to bother checking anything else.( I think they've had alot of defective ones lately.)

For more info on this go to the top of this page and click on the "SEARCH" button. Enter PO401 or EGR or DPFE in the box and you'll find many posts on the subject."

...the DPFE was a dealer item, about $50. It was easy to replace,
probably took less than 10 minutes.

Good Luck,

Gary

 

I did replace the DPFE sensor. Also when applying a vacume to the egr valve the engine rpm's drop.

Paul

 

I just got back from the dealership. They ran a pinpoint test and told me the egr ports are clogged. How accurate is this test and how do you clean the egr ports?

Thanks
Paul