Rear o2 sensor problems

[WRXtreme]

Recently my o2 sensor came unclipped from the rest of the harness. I noticed the CEL came on but didn't catch it right away. The plugs on both ends(one going to the o2 sensor the other to the ECU) were drug on the road and wore down to the point that they can't be reconnected. Yesterday I decided to crawl under the car to try and fix the problem. I stripped the wires on the o2 sensor side, put in some extensions and put connectors on the ends of each wire. When I went to do the same to the wires on the ECU side, the colors were different.

What I need to find what color wires on the ECU side connect to what wires on the o2 sensor side so I can get everything hooked up and clear my CEL so that I can pass emissions.

I've searched NASIOC, Scoobymods, posted on both with no success. I downloaded the service manual for a 2002 impreza but could not find the info I am looking for.


The wires on the ECU side of the plug are Yellow w/ a Red line, Blue, White and White.

The wires on the o2 sensor side are Blue, White, Black and Black.

I am headed down to the beach later today and would like to take my WRX so I don't have to drive my 7-8mpg truck 300 miles. If anyone could find an answer for me that would be great. The only way I know is to have someone crawl under their '03 and pull the cover protecting the wires back to see which wire goes with which wire.

[newtothegame]

That or find someone that has a multimeter to read the current through each of the line. Im not much on electronics, but my friend is an electrician. Thats what he said to do.

[WRXtreme]

I do have a multimeter, but I hate wiring. I have had other people recommend that as well, but don't really know what I am doing when it comes to reading the current.

[pzr2874]

Ask Mike Nagy (nagyhead) He might go under his for you. Send him a PM.

[nagyhead]

I dont know right off hand but i will pull my car in at work today and verify the wires for you.

BTW your refering to the rear o2 right.

[WRXtreme]

That is correct.
These are the colors I am dealing with right now.
The wires on the ECU side of the plug are Yellow w/ a Red line, Blue, White and White.
The wires on the rear o2 sensor side are Blue, White, Black and Black.

Not sure why they are different colors but only reason I could think of was that the o2 sensor is from a different manufacturer.

[newtothegame]

I feel you about not liking electrical stuff. I know a little bit about it, but it makes my head hurt doing it for some reason. I usually have a friend help out.

[wrxshotta]

Originally Posted by WRXtreme

That is correct.
These are the colors I am dealing with right now.
The wires on the ECU side of the plug are Yellow w/ a Red line, Blue, White and White.
The wires on the rear o2 sensor side are Blue, White, Black and Black.

Not sure why they are different colors but only reason I could think of was that the o2 sensor is from a different manufacturer.

nah its not from a different manufacturer i recently swapped out mine and i had the same Blue, White, Black and Black and the yellow and what not on the ecu side... i actually had some one write down which wires were what...i will see if i can locate where i put that paper for you.

[nagyhead]

I just looked under my car and my o2 has 4 wires; white , blue , black and black. My ecu side has blue, white, yellow/red, and a white/black
O2-------------------ecu
white-------------blue
blue ---------------white
black-----------yellow/red stripe
black-------------white/black stripe


that is how it is on my 03. you have 2 whites instead of a blue and a white, so i'm not sure.

[WRXtreme]

Thanks for the help with this. I just got around to getting to work on my car and after reconnecting the battery and letting it idle for about 5 mins, no CEL. I'll let you know how it is after a hundred miles or so. Thanks again!!