2001 F150 5.4L Triton Motor. Everything seemed o.k. then got the Engine Service Light. Checked with reader and above codes only appeared. Read numerous articles/videos and pulled the PCV hose/boot assembly and replaced the whole thing with oem part. Visually checked for disconnected tubing = none found. After this and with the new hose assembly in place I performed a reset. With the scanner still connected restarted engine and read values: ST FTRM1&2 = -.08~+2.3, both oxygen sensor voltages are varying and the LT FTRM1&2 hang around +26 and +28. From what I understand the ST seems o.k. but the long term is WAY OUT OF WHACK. Started it up again and took carb cleaner spray and covered all the connections I could see = no change in engine rpm. No cracks in the air cleaner body. Big plug to the MAF was inserted and plugging the hole. I am thinking of making a smoke "machine" and trying that or removing the hoses from the throttle body and plugging the holes in the throttle body and see if that clears them up. IF it does then connect one by one and keep checking the values. Lot more work but I am at a loss. ANYBODY have any other ideas or suggestions? THANKS for any help offered

 

Look at the freeze frame data when the code was set.


If it was at low rpm and light throttle, suspect a vacuum leak.


If it was at higher rpm and heavy load, and both banks went lean, suspect fuel supply issue.

 

my 2001 had those two codes several years ago. I had two 1/4 inch size black vacuum hoses , about 8 inches long, on the EGR system above the drivers side valve cover fail... The hoses are close to the exhaust manifold, get hot, crack, dry out....... Not saying that is your problem, but I would bet on SOME vacuum hoses... Pull each off one at a time and replace all that are hard / crack / burnt.

 

Thanks for your responses. 'PDQFORD'- I will check the freeze frame and go from there. Steve, I already replaced both of those two lines that connect to the DPFE sensor and the two stainless(?) steel tubing as they were toast. I do appreciate your suggestions. IF anything else should come to mind please pass it on. IF I find the remedy I will post it.

 

If it is a 4x4, check the lines to the actuators right behind the battery. Mine cracked and set off both these codes.

 

I had the same codes/problems. Turned out to be a weak fuel pump.

 

For me it was intake manifold gaskets, but I was able to diagnose it by spraying carb cleaner around the intake.