Nissan Infiniti O2 Oxygen Sensor TRQ OSA61181

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Hi, I'm Don from 1A Auto. I hope this how-to video helps you out, and the next time you need a part for your vehicle, think of 1AAuto.com. Thanks.

In this video, we're going to show you how to replace an upstream O2 sensor on this 2003 Nissan Altima with the 2.5L, 4-cylinder engine. The items you'll need from this are a new upstream O2 sensor from 1AAuto.com, a flat blade screwdriver, a 7/8 inch O2 socket from 1AAuto.com, and a ratchet. In our worst case scenario, we'll also need a pair of wire cutters and a pair of regular 7/8 socket. Because of the location of this O2 sensor, you can't actually use a 7/8 inch wrench, but you do need this special socket with the cut out that accommodates the wires on the O2 sensor. It's the only way to reinstall a new O2 sensor on this particular vehicle. We do sell it; we offer it in kits with the O2 sensor. To remove it, we do end up actually using this 7/8 socket and just cutting the wires, and we'll explain more of that later.

The upstream O2 sensor we're working on is located right here. Disconnect the O2 sensor harness. It's the green connection. You have to press a tab and pull it apart. Now you'll see that the harness is actually clipped on. You just want to unclip that and pull it down. Now here's that special socket, and you just slip it right over the O2 sensor. Now attach your ratchet. That socket is good because you don't have to worry about the wires because they come right out of that slot. The only problem with it is the big slot in it lets the socket expand so if the O2 sensor is in there really tight (like this one is) the socket kind of expands and kind of slips on to the O2 sensor.

What we'll need to do is basically just cut that wire with a set of wire cutters. Then we're going to use a solid 7/8 inch socket and slide it right over there. It has to be a deep socket. Put the ratchet on there and remove the O2 sensor. Just pull the O2 sensor up and out.

You can see the one on the top is the old one and it's in very rough shape. It's actually misshapen. The lower one is the new one from 1A Auto and it's an exact match.

You want to feed your new O2 sensor down into place, and just twist it in by hand to start. Now, you want to use that special O2 socket with cut out for the wires, and just tighten the O2 sensor into place. We'll fast-forward as Don does this. Now reconnect your harness and just clip that connector back up onto that bracket. Now you're all set.

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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.

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