Help a blind man to see!

I go to O'Reilly's today and get 4 (thats how many the guy said I had - keep in mind I hadn't crawled under my truck yet to verify) O2 sensors. I left with 2 different part numbers, and 2 of each part. Two for before, and two for after the converter. He even labelled the boxes "b4" for the two befores....

I get home, the befores are cake to see and almost as easy to get to. I was able to use an open end wrench to break them loose and remove them. However the boxes labelled "b4" had a little 3 in pigtail on them. I opened the other two boxes, they had about a 7 or 8 in pigtail, matching the ones I was removing. SO... I chalked it up as he had mislabelled the boxes (after I called "the zone" to double check part numbers.

Thats not where my problems lie..... The guy at Auto Zone said I only had one after the converter. I've ran my hands on top and around all sides of those darn exhaust pipes from the "before" sensors all the way back to my muffler and there are NONE past the "Y" connection before the converter.

HELP?!? AM I missing the 1 (or 2) past the converter? Is it possible that someone replaced the converter and hence removed the other O2 sensor? I can say that I bought the truck used in '05, but it had a ford factory muffler on at the time (I replaced with a flowmaster).

Where might I find this stealthy O2 sensor?!?

 

You will only have two O2 sensors one on each side of the Y-pipe right after the exhaust manifold flang. Since your vechicle is over 8500lbs GVWR you bascially have and OBD I system that has and ODB II connection. It is not required to have and aft cat O2 sensor. The Motorcraft part number for the O2 sensor is XC2F9F472B1A (DY1040). This number is for a 2000 V10 but I would guess the sensor would be the same for a 2001 5.4. You should be able to have them cross refence the part number from this to get the proper sensor from Auto Zone.

 

I think this is the proper sensor.
AutoZone.com | Shopping | Parts | Product Detail - Oxygen Sensor

 

Monster-4 has you covered. The Superduty is not OBD-II compliant (although some are) and they do not have an O2 sensor after the cat.

https://www.ford-trucks.com/forums/5...t-come-on.html

 

Well, technically, you have OBDII hardware running OBD1 software with only the OBDI-equivalent set of sensors for the >8500# trucks.

Refer to the OBDII Theory and Reference manual available at www.motorcraftservice.com for exact details.

Steve

 

Check out the link I posted above. It winds up in the same place