oxygen sensor removed from downstream exhaust, need help

[mazdamama]

when i bought my truck a few months back it seemed fine, but the guy seemed like he wasnt being completely honest with me either. anyway, i just removed the exhaust and disconnected the negative battery cable for the first time on my 4 litre v6 and since then i keep getting a whole lot of system too lean bank 1 and 2 codes. the guy mentioned that the truck just got a new catback exhaust, and it looked fine until i pulled it off and realized that there was no o2 sensor behind the cat.
so..
Could this be causing problems?

is there a way he might have shut off this code, and it came back on after i disconnected the batery?

how can i reconnect a downstream o2 sensor, or do i have to buy a whole new exhaust or cat setup?

 

[UrbanRedneckKid]

Your truck runs on an OBD1 setup. They only have O2 sensors in front of the cats. The later OBD2 setups 96+ had the post-cat/ downstream O2 sensor only to monitor the performance of the catalytic convertor.

The 4.0 is know for lean codes, but worry about that later.

Start with the simple things like cleaning the Mass air flow(MAF) sensor, making sure the tube from the MAF to the throttle body isn't cracked or damaged, and checking for vacuum leaks.

 

[Yellowsplash]

If it makes you feel better, a missing downstream O2 sensor would not trip that code anyway.

 

[JohnPi]

Is there a hole in the Cat that makes you think there should be another O2 sensor? My '93 only has one O2 sensor before the Cat, but I swapped in a Cat from a '97, and it has the hole for a second sensor after the converter bulge. I just left the sensor there, and it isn't connected to anything. It's just there to confuse someone that doesn't know what's supposed to be going on

 

[85_Ranger4x4]

Lean Bank 1 & 2 codes is usually a intake issue (somehow sneaking more air in than the computer thinks there is) rather than a O2 senser issue. It would very rare for both of them to go out at the same time.

 

[mazdamama]

wow thanks for all of the advice, my manual didnt specify that, so i dint know it didnt have any downstream o2 sensors. well, whats really throwing me off is the extra sensor connector near the two o2 sensor connectors above the transmission. maybe this is the source of the code. i have a third plug near the 02 connectors but unlike the o2 sensor connectors, its black and i cant seem to find where it goes. i just assumed that it would go to an o2 sensor behind the cat, but i guess im wrong. i already cleaned the filter and MAF sensor, as well as replaced the o2 sensors after i received these codes but they still keep popping back on. but ive only visually checked the vacuum hoses, i should still do a smoke test or something to find the leaks.