TRQ oxygen sensors are manufactured to precise specifications using premium raw materials to optimize your vehicle’s emission system. Each sensor is isostatically-pressed for improved strength and durability, and plasma-sprayed to improve sensitivity and prolong the service life of the sensors. Oxygen sensors wear out over time and should be replaced every 60,000 miles to prevent poor engine performance. TRQ recommends replacing the oxygen sensors in sets to optimize fuel economy and reduce overall emissions. All products are fit and road-tested in our Massachusetts R&D facility to ensure we deliver on our promise of Trusted Reliable Quality.
Product Features
Application Specific Design: No modifications and pre-calibrated
Isotatic-pressed and plasma-sprayed for extended service life
Double-Layered 310S Stainless Steel: Additional protection from moisture and debris
Restored Engine Performance: Improved fuel economy and lower emissions
What is Upstream vs. Downstream?
Upstream location is between the catalytic converter and the engine
Downstream location is between the catalytic converter and the tailpipe
Install Tip: You may be required to reset the vehicle computer after installation of this part.
Quality Tested - built to a strict level of product standards.
Item Condition:New
Attention California Customers:
WARNING: This product can expose you to chemicals including Lead and Lead Compounds, which are known to the State of California to cause cancer, and birth defects or other reproductive harm. For more information, go to www.P65Warnings.ca.gov.
Lifetime Warranty
This item is backed by our limited lifetime warranty. In the event that this item should fail due to manufacturing defects during intended use, we will replace the part free of charge. This warranty covers the cost of the part only.
Returns: Parts with electrical components cannot be returned once installed.
FREE Shipping is standard on Orders shipped to the lower 48 States (Contiguous United States). Standard shipping charges apply to Hawaii, Alaska and US Territories. Shipping is not available to Canada.
Expedited is available on checkout to the United States, excluding Alaska, Hawaii and US Territories as well as P.O. Boxes and APO/FPO/DPO addresses. Final shipping costs are available at checkout.
O2 Sensors is it Upstream or Downstream
Created on:
Tools used
No Tools Needed
1. Identifying your Oxygen Sensors
Upstream oxygen sensors are located in between the engine and the catalytic converter
Downstream oxygen sensors are located in the catalytic converter or farther away from the engine than the catalytic converter
Locate your vehicle's firing order diagram
The bank that contains cylinder one is bank one
The bank that does not contain cylinder one is bank two, even if it does not contain cylinder two
Hi, I'm Mike from 1A Auto. We've been selling auto parts for over 30 years. We're dedicated to delivering quality auto parts, expert customer service, fast and free shipping, all backed by our 100% satisfaction guarantee. Visit us at 1AAuto.com, your trusted source for quality auto parts.
In this video I have a couple of oxygen sensors with me. While there are some aesthetic differences here, the wire lengths are a little different, the actual body and tip of the sensor are a little different, the threads and gasket are the same, and on the other end the connections are actually the same. I can plug these into either position on our vehicle. But if I had to ask you which one's upstream and which one's downstream, you probably can't tell just from looking at them. That's true of most oxygen sensors. The way you determine whether or not an O2 sensor is upstream or downstream is all done visually.
Your oxygen sensor position can be determined relative to your catalytic convertor. As the name suggests, upstream sensors will be located upstream or ahead of, in front of, above, closer to the engine than your catalytic convertors. This means that they see the exhaust gasses first. They then go through the catalytic convertor and to the downstream oxygen sensor, which will either be located in the catalytic convertor like our vehicle here, or after the catalytic convertor to monitor the gasses coming out of the cat and make sure that it's being efficient relative to the readings of the upstream O2 sensor.
The other determination you need to make is bank one versus bank two. Determining which bank is which can be done by looking at a picture of your vehicle's firing order. Whichever bank contains cylinder one is going to be bank one, and the other one, regardless of whether or not cylinder two is in it, is going to be bank two by default. These banks are true of V engines like V8s, V6s, and flat engines like Porsches and Subarus that have individual banks.
On inline four-cylinder engines, as long as they have one exhaust manifold like a Jeep four-liter or a four-cylinder Honda engine, you'll only have one bank with an upstream and downstream O2 sensor. There will be no bank two on the engine.
On our vehicle here, this is the passenger side, which we've already determined from the firing order is bank one. We have our upstream sensor here closest to the engine ahead of the cat. Then we have our downstream or sensor two here inside of the catalytic convertor. This could also be located somewhere after the cat. Here I have my two sensors for the vehicle. While they are aesthetically different, we can now tell this is my upstream sensor because it looks just like the upstream sensor I have up there. This is my downstream sensor. Now that we know which one's which, we can order the right part, correct the problem, and fix you up right.
Thanks for watching. Visit us at 1AAuto.com for quality auto parts, fast and free shipping, and the best customer service in the industry.
OSA61214
In Stock
Product Reviews
Loading reviews
4.29/ 5.07
7 reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
5
1
0
0
1
this sensor failed in 1 month of use
mark
March 12, 2017
this sensor failed in less than a month of use had to replace it with autozone 56.00 dollar cheap brand dont buy this one
O2 sensors
Michael H
September 25, 2017
installed and seem to be working fine. Recommend a mechanic do this job unless you have a hoist and easy standup access. remind all purchasers that these are very fine threads holding the sensors in and after 150k miles of NE winters it is a time consuming and careful install. Now chasing down a vapor system light.
24/7
D
September 3, 2019
1A auto is awesome, easy shopping free shipping get the parts you need and save money. I have ordered several parts and was completely satisfied on all of them.
fantastic
Mark
November 6, 2019
quick and easy.
Hazel
March 17, 2023
Perfect fit, that is why I call on you for my parts
Fantastic for 2007 avalanche 5.3
Jesse
June 14, 2023
Came quickly And was an exact replacement. I would recommend the removal socket.
Johnnie
January 14, 2024
Great product
Customer Q&A
Is this sensor used for both upstream and downstream?August 20, 2017
B R
10
No it is not. I made this mistake a few months ago. One connector is female and the other is male. So make sure you get the correct one. Hope this helps
August 20, 2017
Michael V
10
This sensor will work exclusively for a downstream or upstream depending on your application.
August 21, 2017
Tim K
10
I have a 2004 honda civic ex with the 1.7 engine and the upstream is a different connector then the downstream. This part will fit the downstream only on that model civic
September 23, 2017
Ben P
10
It's a sensor for a t100. It only fits downstream.
January 13, 2019
T H
I see it hits a 07 chevy suburban 1500, but not seeing the engine size. Does the engine size matter for Oxygen downstream sensor?May 6, 2019
Princess W
10
The engine size would not matter for this part. Thanks!
May 6, 2019
Adam G
Wher is the oxygen sensor 2003 Saturn l200?February 5, 2022
John D
10
Hello, I apologize we would not have that type of information here. You could check your owner's manual.
February 5, 2022
Ricale A
Customer service
877-844-3393
Monday - Friday 8:00am - 9:30pm ET Saturday - Sunday 8:00am - 4:30pm ET
Chevrolet is a registered trademark of General Motors Company. 1A Auto is not affiliated with or sponsored by Chevrolet or General Motors Company.See all trademarks.
Enter Vehicle Year Make Model
Specify your vehicle's year, make and model to guarantee fit.
Year
Make
Model
Options
Drivetrain
This part doesn’t fit a . Select from parts that fit.