Hello all,

4.6L 200, 168k miles with a P0401 code that won't go away. TB removed, thoroughly cleaned, replaced. Vacuum lines replaces. EGR replaced. I mean you name it, if it's even remotely related to the issue it was replaced or thoroughly cleaned.

P0401 will clear, drive the truck as usual for about three to four days, and the dode comes right back.

What am I missing?

 

Did you make sure the EGR passages were fairly clean ? They do have a tendency to get blocked with carbon and did you verify vacuum is getting to the EGR valve ?

 

 

Hanky,
Thank you for your response. In a word, yes.

Checked voltage (all good) to the various components, removed throttle body / idle air control and thoroughly cleaned.
Replaced EGR and solenoid, DPFE sensor, vacuum lines .

 

Thanks.

1) '01 - F150 - 4.6L - 2WD - Auto.

2) See original post

 

Checked voltages ?? Where ?

Do we know if the signal from the PCM is being sent and if it is getting to the EGR solenoid which should if open, should cause the EGR valve to open ?

If you apply vacuum DIRECTLY to the EGR valve when engine is idling , the engine should falter, want to stall, Does it ?