service engine soon light came on today. I received the following codes P0171,P0174,P0301,P0401. Where do i start to look for the problems.


2001 F150 XL
4.2L

 

P0171- System Too Lean (Bank 1)
P0174- System Too Lean (Bank 2)
P0301- Cylinder #1 Misfire Detected
P0401- Insufficient EGR Flow

Google is your friend.

 

There is a TSB for the two codes pertaining to the lean mixture. Check out the thread by msteele516 on 07-13-08. Its an excellent thread, covering the subject fully, believe his comment, "a ten minute job taking 2 hours". believe what he says, it took this old man the two hours plus a bunch. The PO401 pertains to the DPFE sensor. That used to be replace under warranty. I was past the warranty time, about $60.00 and more time to find the sensor then changing it. No comment on the last code (unfamiliar).

On a personal note, stay away from the changing the 02 sensor advice, that I am sure is comming your way, more 02 sensors have been changed needlessly, than ever were installed off the assembly line.

 

Ive got the same codes on my 98 4.6. I have been trying to get rid of them for a while with no luck. Keep me updated on what you end up coming up with and Ill post on here if I get mine fixed

 

Fixed!!! installed new pcv valve,egr vacuum regulator,DPFE sensor.Drove about 75 miles no light. thanks everyone!!!!!!