At a loss

[FreeWheelin4x4]

And confussed


Ok, despite searching I seem to come up with two different meanings for the codes, and even many different solutions to the codes.

Let me start by giving a brief history.

I have a 95 XLT 4.0 3.55 gearing (if it matters)

I started (about 3 months ago) getting an intermittant CEL while driving, usually comes on after the engine is warm and about 20 minutes of driving, then it'll go out 5 minutes or so later, and stay off for another 10 minutes then come back on. I have tried a new gas cap, no avail. So I pulled the codes today using the sticky article in this section of the forums.
I have NO drive issues, NO idle issues, my truck idles at about 700-1100 RPM depending on if it's a cold engine or warmed up. The only issue I am aware of in my truck is needing new shocks, which are being replaced next week with RS5000's....in any event, here's the codes that came up:

KOEO
335 - EGR Feedback signal Is/Was out of Range

CM
172 - Oxygen Sensor not switching - System is or was lean - Single, Right, or Rear HO2S

KOER
326 - PRessure Feedback EGR shows low pressure EGR not seating or not seating intermittantly

632 - E40D Transmission control switch should be cycled once between engine ID and Goose Test (I did do this prior to punching the gas briefly and this code went away on the second test with no additional codes)

SEFI
9 - NO CLUE WHAT THIS MEANS

Now, from what I've seen throughout the forums say it's my EGR, while others say it's not the EGR but rather an electrical sensor.

I'm confussed, what should I do, should I replace my EGR? All the lines seem to be in place without chipping and deterioration. All electrical wires seem intact without deterioration. What's up with that SEFI code? I couldn't find anything worthwhile about it anywhere, it cycled as it should while doing the test, and gave me 9 blinks, paused about 6 seconds and another 9 blinks then stopped completely, test done I guess.

Any help would be greatly appreciated. My gas mileage is fine at about 17-21MPG highway (most of my driving), again no idle issues, no bogging issues, no power loss issues, nothing....should I even concern myself with it?

Thanks in advance!

-FreeWheelin

 

[ExplorerDMB]

326 - Egr (EPT) circuit voltage lower than expected (PFE)

for code 9 - there is no listing for that code.

-Drew

 

[MrShorty]

SOP when resolving EEC-IV codes: Resolve KOEO codes 1st, then resolve remaining KOER codes, then work on CM codes. So we start with the KOEO 335

KOEO 335: Because KOEO codes are set with the engine not running, they almost always have to be electrical in nature. This code is usually set by a fault in the DPFE sensor or it's associated wiring. In short, I think the usual diagnostic procedure for this code is to verify that the wiring between the DPFE and the computer is intact. If it checks out then check/replace the DPFE.
Because the other codes could easily be caused by a bad EGR signal, start there.

Note on the SEFI 9. Your computer is able to perform a cylinder balance test after the KOER test. I have no experience with this test, but you must have triggered the test after the KOER test. 9 (or 90 on some scanners) is the computer's way of saying that it passed the cylinder balance test: all cylinders are contributing equally.

 

[FreeWheelin4x4]

Cool deal MrShorty, appreciated. Will be working on that tomorrow when it's not so crappy out.