About TRQ: TRQ is a trusted brand dedicated to making every repair a success story by combining premium parts with easy installation. Each TRQ part is engineered by a team of automotive experts to meet or exceed OEM standards, delivering enhanced performance and maximum longevity. With rigorous in-house testing, the brand ensures superior fit and function across every product line. TRQ also provides customers with best-in-class, step-by-step installation videos—so you can complete repairs with confidence, whether you're a first-time DIYer or an industry professional.
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
Description
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.
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.
Returns: Parts with electrical components cannot be returned once installed.
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.
This part fits
7 vehicles spanning 1999-2004.
Fits these Makes
Select vehicle
Year
Make
Model
Description
1999
Toyota
4Runner
Toyota 4Runner V6 3.4L with California Emissions Manual Transmission Upstream O2 Oxygen Sensor TRQ OSA61231
2000
Toyota
4Runner
Toyota 4Runner L4 2.7L with California Emissions Automatic Transmission Upstream Bank 1 Sensor 1 O2 Oxygen Sensor TRQ OSA61231
2000
Toyota
Tacoma
Toyota Tacoma V6 3.4L with California Emissions Manual Transmission Upstream O2 Oxygen Sensor TRQ OSA61231
This item may be interchangeable with parts from other brands with the above part numbers.
This information is provided only for reference and does not guarantee that the item you are
purchasing is identical to parts with part numbers from the brands listed above.
To confirm that this item fits your vehicle, use the above "Check Vehicle Fit" option.
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.
Is my Car a California or Federal Emissions Vehicle
O2 Sensors is it Upstream or Downstream
Created on:
Tools used
No Tools Needed
1. Determining Your Emissions Specification
Open your hood
Locate your catalyst sticker
If the sticker says "This vehicle conforms to California regulations," you have a California emissions vehicle
If the sticker says "This vehicle conforms to US EPA regulations," you have a federal emissions vehicle
If the sticker lists both EPA and California regulations, you have a California emissions vehicle
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.
Determining whether or not your vehicle is a California emissions or a federal emissions vehicle is pretty straightforward. To do this, you'll want to locate your catalyst sticker under the hood of your vehicle. It'll either be actually on the bottom side of the hood, most GM vehicles have it on the air box, and other vehicles may have it along your radiator support at the front of the engine bay.
All you need to do is see, "This vehicle conforms to California regulations." That means that this vehicle is a California emissions car. Just because you're not in California or are in California doesn't necessarily mean your vehicle will be one way or the other.
Now, our F150 has it down here on the radiator's support, right at the front of the engine bay and you can see here, "This vehicle conforms to US EPA regulations." This means that this vehicle is a federal emissions.
Now, here we have two things that are a little different. Our catalyst is located on the vehicle's air box and this vehicle conforms to US EPA regulations and California regulations. If it conforms to both federal and California emissions, it's considered a California emissions vehicle.
Thanks for watching. Visit us at 1AAuto.com for quality auto parts, fast and free shipping, and the best customer service in the industry.
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.
OSA61231
In Stock
Product Reviews
4.3/ 5
★★★★★★★★★★
23 reviews
5★
74%
4★
9%
3★
0%
2★
9%
1★
9%
★★★★★December 5, 2022
Awesome
Love the price and free shipping......
★★★★★September 13, 2022
Fits great. Cost less than auto parts store.
★★★★★December 25, 2021
The sensor fit like the original part. The engine is running like before the original sensor went bad.
★★★★★October 27, 2021
I would buy from somewhere else
It didnt work. Unplugged the battery, waited 15min, then installed the O2 Sensor. Started the car and it check engine light still on and the exhaust stinks even more. Waste of $75. Spent a little more on Denso Sensor for $105 at auto zone and it worked perfectly.
★★★★★October 25, 2021
Same as OEM
Great worked perfect, check engine light hasnt been on since I installed it
★★★★★June 14, 2021
Happy customer
Sensor was correct fit and worked perfect
★★★★★December 30, 2020
No good
Not worth it. Worked for about 3 months then failed (verified with olm reading)
★★★★★June 27, 2020
Zero if I could
Absolute garbage. Had a check engine light since replacing. Keepa popping up every 2p miles. Even after trying to call and email to get my money back this company wont reply. Avoid
★★★★★April 9, 2020
O2 Oxygen Sensor
I would recommend 1AAuto to anyone looking for great parts and great prices. The O2 Oxygen Sensor works as advertised. Perfect fit and corrected my problem.
★★★★★April 9, 2020
Fast delivery
Fast delivery and the right part. Good price too
Showing 1–10 of 23 reviews
Customer Q&A
Got a question about this part? Post it and get answers from our team.
RuddyMarch 3, 2022
How long is cable?
Overall Length: 17.72 in
Andra · March 3, 2022
BrandonNovember 8, 2019
Is this the part that I need for code throwing p0125?? 2001 Toyota Tacoma 2.7
It worked for me but mine was a 3.2 v6 but they are probably the same o2 sensor.
C · November 9, 2019
RexFebruary 2, 2019
Will this fuel air sensor work on California emission ?
It will be compatible with California emission vehicles.
Corey · February 2, 2019
GregJuly 3, 2016
will this part work with a manual transmission?
Yes
derrick · February 23, 2019
Showing 1–4 of 4 questions
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