Ford Mazda Lincoln Mercury O2 Oxygen Sensor Walker Products 250-24701

Okay, friends. To get started on our upstream O2 sensor, you're gonna find that there's one on the driver's side bank and there's gonna be one on the passenger side bank. The process is gonna be about the same for either side, I'm gonna be working on the driver's side.

One of the first things that I always like to do is disconnect the wiring for it. If you look right along here, you're gonna see a grey harness, use your small pocket screwdriver or you can, of course, use your thumb if you wanted to. Come right in between here, press down on that, and then separate the two. I always like to look inside to see if there's any funny colors, you can use a mirror if you need to look up in that one. Set that aside, now we're gonna remove the O2 sensor from the exhaust pipe.

Next, you're gonna need a socket that looks like this, this is an O2 sensor socket and you can see that it has a slot right there. I'm gonna come right over the wire and put that right onto the O2 sensor itself. Now, I'm gonna use my ratchet, and I'm gonna turn that counterclockwise and remove it from the exhaust. Let's put that right in like that.

A lot of times with your ratchet if you're lucky enough, you can get it to come out and through towards that wheel well. I like to go through the wheel well because it just gives me a little bit more leverage rather than trying to reach down in here and see if I can do it. There we are. I got it so it broke free. Once you have it loose, you should be able to unscrew it. There it is, friends.

Now, it's gonna be time to put in our new upstream O2 sensor. You're gonna notice that on the threads there should be a little bit of Never-Seez. Leave that on there but be careful not to get on the sensing agent down at the end. I'm just gonna start this in by hand, which is very important to always start things in by hand so you can make sure it's not gonna crust right in. I'll snug it up as much as I can and then of course, I'll tighten it up with my ratchet and socket.

Now, we're just gonna tighten this up. You wanna go until you feel as though it bottoms out which is right about there, I can feel like it doesn't want to go too much further, I'm just gonna give a teeny bit more just to make sure that that gasket is nice and crushed down. Remove our tool. Now, I'll grab our wire, make sure that it isn't twisted or anything.

Of course, attach it in. It should click and give it a nice tug to make sure it's secure, and then of course, just make sure that your wire isn't any place near the exhaust in any way. Okay, friends so you finish your O2 sensor, great job. Now what you need to do is if you had a check engine light on, clear that code. Take your vehicle for a road test. If your check engine light stays off, you did great.

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.