O2 Sensors.....

Just recently went to replace my O2 sensor and when I went to the manual and to the local Auto shop they both said it needed a 1 wire o2 sensor. The problem is, for some reason, mine has a 4 wire o2 sensor.
I pulled apart some of the wiring loom n found that it looked as tho someone had wired it in n changed it.
I have no idea if this is even truely possible, have any of you ever heard of this?
I've been getting shithouse fuel economy, n I was thinkin that this could be the cause?
Could it be that the different O2 sensor gives different readings to the other?
Perhaps the ECU in the celica doesn't understand the O2 sensor I've got and has reverted to the non-O2 sensor map. I do know that before I replaced the O2 sensor, it was running quite rich, but I haven't been able to check the new one coz I'm in the middle of some extensive modifications.

So, basically, I'm using a V6-camry 4 wire O2 Sensor in an alltrac / GT4 thats sposed to have a single wire. Any help would be great. sorry for the long post.

how many wires are on the o2 sensor plug?? (loom end)
if its just one then its a jdm harness/poss engine etc...
so you will need to get a single wire o2 sensor. (i have one)
and yes it will affect your fuel economy..

HTH

The harness has the 4 pin plug on it. As I said, I pulled some of the wrappin n shit off the loom n it seems as tho it's been soldered in.
Is this even possible?
How will it affect fuel economy?
Will the 4 pin be more fuel economical or the single pin?

is your car jdm or have you put a jdm engine in or previous owner etc...
with the loom end of the plug are there four wires going to it?
if so then you need a 4 wire o2 sensor.
if its just one wire going to the plug then you need a single wire o2 sensor.

can you post a pic??

A 4-wire O2 sensor outputs the same signal as a 1-wire O2 sensor when they are both at operating temperature. The advantage of the 4-wire O2 sensor is that the self-regulating heater in it will keep it at the proper operating temperature when the engine is operating under light loads. The 1-wire sensor can cool down under light loads and, as a result, it will output a lean signal... which the ECU will try to richen up.

If you have a good working 4-wire O2 sensor, keep it, but make sure the heater circuit is wired and operating correctly, otherwise it's no better than a 1-wire sensor.

and i wish i knew these things a long time ago...bout 6 months ago i bought a new one for my car with the JDM motor...100 bucks down the tube. could have used a 1 wire 35 dollar POS o2 and been the same.