Just got a 99 Taurus

Just got a 1999 Taurus, runs and looks great, 139k miles and im getting the infamous P0401 emmisions code. I dont know too much about these cars yet. I have read around and it seems that either the EGR valve or the DPFE sensor can trigger this code. the car starts and idles fine no stalling or rough acceleration. that is the only code i get. should i replace the EGR first and go from there if the light comes back?

try cleaning out the egr valve before buying new, carbon collects inside it. Also one of the more likely sources is the dpfe, check to see if it is metal or plastic. The metal would most likely be original on the vehicle and if it is plastic, it has been replaced at some point. Also make sure to check all the rubber hoses that connect in the egr system, over time they crack, melt or rot and can cause a code in the egr system.

ok ill clean it first. i checked the dpfe sensor and it looks to be metal. the light came on this afternoon then it went back out on the drive home tonight, though it will probably come back. whats best to use to clean the egr?

Clean ERG with throttle body cleaner.

I've found the STP Throttle Body Cleaner to cut through the crud quite nicely. I would be more prone to suspect the DPFE over the EGR valve itself though.

It sounds like you've searched the forum, but didn't you find other issues that may cause the P0401? I seem to remember others.

-Rod

Havent found any other obvious signs yet, i figure to start with cleaning the egr and see if that helps if not than suspect the dpfe sensor and go from there.

Edit: so i cleaned the egr, reset the code and the light came back shortly after. is there anything else i should be checking besides the egr and dpfe sensor? the car runs fine, starts right up, idles and accelerates smooth, that is the only code i am getting also.

Hoping someone can help still, i now replaced both the EGR and dpfe sensor reset the light and still getting the 0401 code. Am i missing anything here? the car accelerates, idles and starts up fine.

You may want to check the passageway through the intake manifold. If you have replaced everything else this will probably be plugged up. I do emissions here in S. C. PA and have found that if the DPFE sensor isn't bad the manifold is usually plugged up. A quick way to check it is to take off the EGR valve and try to start it. The engine will stay running if the manifold is plugged but will die if there is a flow through it. This isn't 100% but it can point you in the right direction real fast. Good Luck

Now that you mention it the car did stay running when i had the egr off when i was replacing it.