o2 sensor 3 wires or single wires?

[Ren]

my car is a 95 240sx se. and I need a new o2 sensor. but this store is asking my about single wire one or 3 wires. I have looked at my o2 sensor. It looks like it's single wire. I think the date states on my door is late 94. any idea? thanks

[DAEDALUS]

I think your car is OBDII or almost entirely OBDII. It most likely has 2 O2 sensors. The front one, closer to the engine, is a single wire. The rear one, past the cat, is heated (3 wire). Which sensor do you need? Did you blow a code?

[Ren]

I am not sure, i just recently seafoam my engine. I think I need a new o2 sensor since my car is running extremely rich. but do i need to replace both if my car have 2 o2sensors

[DAEDALUS]

The first o2 sensor is the feedback to the ECU for fuel trim. The 2nd is there just to tell how good a job the cat is doing. If you don't have a check engine light, you don't need the 2nd one.It only started running rich after the seafoam? Really best to get the car on a scanner to determine exactly what the problem is. One time cost, vs throwing parts at the car hoping one will fix the problem. (Are you certain it's not MAF or temp sensor related?) If the O2 is just fouled up warm up the engine and then drive the piss out of the car to burn off the carbon.

[Ren]

I am in the process of seafoaming the engine i should say. My car've running extremely rich since I got her a month ago, about 15m/g city. So, I follow the mothed of how to make your car runs like new. so, I think after the process, The o2 sensor will go bad and needs to be changed, or it's already been fouled. I am a complete newbie on machanical stuffs. Can you tell me more about the MAF or any other issue would cause running rich? thank you

[DAEDALUS]

Best to use the search function, and get your hands on a service manual if you can. Could be quite a few things, both electrical and mechanical in nature. Pull the plugs for clues.

[Ren]

I searched on the o2 sensor already, the posts came up didn't reallie talk about single or 3 wires. So, I just make a post that discusses it

[eddiec]

after i seafoamed my o2 was pretty caked up. in my 91 it only has one sensor and its a 1 wire. just unplug yours and take it to the store to match it up. you probably only need the first one by the header.