Hey,

My SERVICE ENGINE SOON light is on, code reads P0401.

I have a 2003 F150 4.6 with 212k miles. I tried Sea Foam in the tank and sprayed the throttle body and vacuum lines with a throttle body cleaner but light came back on after clearing the code.

Any idea what else I can do?

Thanks

 

Why would expect any of that to affect the EGR system????

Did you even research that fault code? Plug it into SEARCH box, there will be hundreds of posts about it. It has been a very common fault for over a decade and a half.

 

WOW! Thanks for your help buddy. Got to love a response like this!

 

Remove the throttle body and clean out the EGR passages in the elbow. If that doesn't fix it, look at the DPFE and its hoses. Can also be caused by a rotten EGR pipe where it connects to the exhaust manifold.

 

https://www.obd-codes.com/p0401
The 4.6 is notorious for pluggin egr passages. Clean them out like glc suggests.

 

Thanks for the info. I did one better. I just order a new EGR from Rock Auto for $50. But will check the pipe and remove the TB and clean it. The TB was really black inside so it needs a good cleaning.

Thanks

 

A new EGR valve probably won't fix it. It's most often plugged passages or a faulty DPFE.

 

You ever hear the one about teaching a man to fish? I told you how to fish and what to use for bait. What, you were expecting a handout?

Good luck....

 

I am sort of having the same issue. I own a 2005 F150 4.6L. I have a check engine light and lots of codes but my mechanic narrowed it down to an EGR problem (P0401). I have tried everything like you have. My truck has a rough idle with a coughing sound coming from the exhaust. The truck shakes when accelerating and when I get to about 50-55 MPH it seems to loose power. Today while test driving it after cleaning throttle body and plenum, the check engine light even started flashing. It will sometimes stall when decelerating. I also notice white smoke (exhaust gas leak) coming from under the passenger side of the engine which seemed to be from right above the first cat on that side. I have replaced the EGR Valve, MAF, throttle body censor, cleaned throttle body and plenum (made sure to get the EGR port clean), replaced plugs. My mechanics only other guess is to take off the intake and clean the egr ports in there and then replace the gasket since i have signs of a bad gasket. That bad gasket could also be ruining my coils. I'm kind of stuck. Any thoughts anyone?