There are affiliate links on this article. If you make a purchase through any of the links, I may earn a small commission at no extra cost to you.
Can I use a downstream oxygen sensor for upstream? Generally, O2 sensors function similarly, but sadly, they cannot be used interchangeably. Yes, the sensors vary in their threading/wiring patterns, so you have to watch out for that.
To get started with this article, what is an upstream oxygen sensor and how does it differentiate from a downstream oxygen sensor?
In simple words, a downstream O2 sensor is the one installed after the catalytic converter – usually before the muffler, while an upstream O2 sensor is the one installed before the catalytic converter (between the manifold and the CAT).
Can I Use a Downstream Oxygen Sensor For Upstream?
When buying oxygen sensors, they are always labeled “Upstream” or “Downstream,” and that’s because they cannot be used interchangeably; you need to get an upstream sensor for the front installation and a downstream sensor for the back installation.
The “front” and “back” meant here are “before” and “after” the CAT, respectively.
You shouldn’t use a downstream oxygen sensor for upstream installation; if you do that, your car may show the check engine light because the ECU wouldn’t receive the wrong readings from the sensor.
Read Also: Upstream Vs Downstream Oxygen Sensors
Each sensor – upstream or downstream – is designed specifically, even though they perform the same similar function.
More so, the threading pattern of these sensors differs; while upstream sensors thread into your exhaust manifold, downstream sensors thread into the catalytic converter.
Usually, there are two upstream sensors and two downstream sensors in modern vehicles, you can use upstream oxygen sensors interchangeably when installing them between the manifold and catalytic converter.
In the same way, you can use downstream oxygen sensors interchangeably when installing them after the CAT.
But to take a downstream oxygen sensor and install it in the position of upstream sensors, that’s not advisable at all; it can cause poor engine performance, and your check engine light may come on.
Furthermore, downstream sensors are practically the same on every vehicle, which implies to say that you can use a downstream sensor on any vehicle, provided the thread/size matches.
Are There Universal Oxygen Sensors?
All oxygen sensors perform the same function but at different positions. You can say they are universal because you can use any downstream O2 sensors at the “downstream” position on any vehicle, as long as the threading pattern of the sensor matches that of the vehicle.
Changing a faulty or damaged oxygen sensor should be done by a professional mechanic so as to ensure that the wiring is done perfectly to prevent glitches and sending wrong information to the ECU, which could lead to a drastic drop in engine performance.
Summary
Typically, upstream oxygen sensors have a square shape at one end while downstream oxygen sensors are round. So, for the question, “Can I use a downstream oxygen sensor for upstream?” The simple answer is NO, you can’t use them interchangeably.
If you interchange oxygen sensors, you’d definitely have to force them to fit in, and that could cause expensive damage. You can buy downstream oxygen sensors from both online and offline auto stores.