2003 Toyota 4Runner V8 4.7L Downstream Left O2 Oxygen Sensor TRQ OSA61308

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In this video, we're going to remove and install the forward oxygen sensor. This is a 1998 Toyota Camry with 2.2L 4-cylinder engine. The only items you'll need are an O2 sensor socket which is available at 1AAuto.com, a ratchet, and a torque wrench.

Open the hood and secure the hood prop. Locate your up-stream O2 sensor and the connector. Squeeze the tab in, remove the electrical connector, undo the keeper to the wire, and allow it to hang. We'll be using our O2 sensor socket, available from 1AAuto.com. If you don't have one, you can purchase one from our website or use a 22mm wrench.

Install your O2 sensor socket over the sensor. We're using a 3/8" drive ratchet on ours. Break the sensor loose and remove it from the exhaust. If you're reusing the sensor, be sure that the wire for the pigtail doesn't get caught anywhere and tear.

Once the sensor's loose, you can finish removing it by hand. Start the sensor in by hand, into the exhaust, then using your O2 sensor socket, tighten the sensor down. Be sure to watch for the harness to make sure it doesn't get caught and tear any of the wires. Torque the sensor to 32 foot-pounds.

Reinstall the connector. Make sure that it clicks in and locks fully. Now, we'll use this retainer to hang the wire off the upper radiator hose. It's got all the teeth that lock together. Tighten it up.

To remove it, just release the tabs.

Reinstall the retainer to hang the sensor wires form the upper radiator hose.

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Remove the downstream O2 sensor. I'm going to follow the wire up here and unplug it from the connector. There's a white part on the connector, and I'm going to push in to unlock it. Pull the gray part out. Now I can work on getting it out of the exhaust. Spray some rust penetrant in here. The exhaust is pretty cool. It's a 22 millimeter, so I'm going to slide the box end over the connector and down. There's actually enough space to get a wrench in here, so maybe use a spark plug socket. Give a good pull. Once it breaks free, I'll just unthread it from the exhaust.

And replace the sensor. This O2 sensor is fine. We're going to reuse it. If you were replacing the exhaust, you could take it out and put it back in. But I'm just going to put a little bit of copper anti-seize compound and then reinstall it. I'll wipe off the extra rust penetrant so it doesn't get smelly when the exhaust heats up. And install our sensor. Get it lined up. Just thread it in by hand. Put the box end through the connector. Tighten it down. Just want to feel that gasket squish a little bit. That's installed. The final step: go up, plug it back into the connector. It clicks. It locks into place.

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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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