# Need o2 sensor help (down-stream)

**URL:** <https://forums.speedlife.net/t/need-o2-sensor-help-down-stream/252314>\
**Category:** Shift518 Automotive\
**Created:** [May 27, 2010, 9:15am UTC](https://forums.speedlife.net/t/need-o2-sensor-help-down-stream/252314 "2010-05-27T09:15:30Z")\
**Posts on this page:** 1\
**Showing post:** 7

<div class="post-metadata">

**Author:** ![ninety1two40](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ninety1two40/32/6332_2.png) [@ninety1two40](https://forums.speedlife.net/u/ninety1two40)\
**Post date:** [May 27, 2010, 4:43pm UTC](https://forums.speedlife.net/t/need-o2-sensor-help-down-stream/252314/7 "2010-05-27T16:43:55Z")

</div>

> [@FS: 1992 GSR "Low Miles" "PICS"](https://forums.speedlife.net/t/fs-1992-gsr-low-miles-pics/32133/47):
>
> not sure if it helps at all, but its a 4 wire sensor. 2 white (heater), gray, and black. So if it is + on simulator/sensor and - on chassis, is gray or black the +?? I am good when it comes to electrical, but I dont have an idea in the world how an o2 sensor works… lol

Put your meter’s red lead on the gray and the black lead on the black.

---

_[View the full topic](https://forums.speedlife.net/t/need-o2-sensor-help-down-stream/252314)._