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How to Replace Upstream O2 Oxygen Sensor 10-15 Toyota Prius

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How to Replace Upstream O2 Oxygen Sensor 10-15 Toyota Prius

Created on: 2018-04-12

How to remove, install, change or replace an oxygen O2 sensor on 11 Toyota Prius.

  1. step 1 :Removing the Wiper Arms
    • Pry the cap off the driver side wiper arm stud
    • Remove the 14mm nut from the stud
    • Pull the wiper arm off the stud
    • Open the hood
    • Remove the two 14mm mounting nuts from the passenger side wiper arm
    • Pull the wiper arm off the windshield
  2. step 2 :Removing the Cowl Cover
    • Pry off the two cowl corner trim pieces with a trim tool
    • Pry the two push clips out of each side of the cowl with a flat blade screwdriver
    • Release the clips along the front of the cowl
    • Lift the cowl up and out of the engine bay
  3. step 3 :Removing the Wiper Transmission
    • Unplug the wiper motor electrical connector
    • Unclip the wiring harness from the lower wiper cowl
    • Remove the four 10mm bolts from the wiper transmission
    • Pull the wiper transmission off the lower wiper cowl
  4. step 4 :Removing the Oxygen (O2) Sensor
    • Remove the nine 10mm bolts from the lower cowl panel
    • Remove the lower cowl panel
    • Pop the wire out of the hook
    • Disconnect the electrical connector
    • Remove the O2 sensor with an O2 sensor socket and 3/8 drive ratchet
  5. step 5 :Installing the Oxygen (O2) Sensor
    • Place copper anti-seize onto the new O2 sensor
    • Insert the O2 sensor into place
    • Set the wiring into place
    • Connect the electrical connector
    • Insert the lower cowl panel into place
    • Tighten the nine 10mm bolts to the lower cowl panel
  6. step 6 :Installing the Wiper Transmission
    • Line up the wiper transmission
    • Insert the wiper transmission pin into the rubber grommet
    • Insert the four 10mm bolts into the wiper transmission
    • Plug in the wiper motor electrical connector
    • Clip the wiring harness to the lower wiper cowl
  7. step 7 :Installing the Cowl Cover
    • Slide the cowl under the windshield
    • Push in the clips along the front of the cowl
    • Insert the two push clips into each side of the cowl
    • Clip the corner trim piece onto each side of the cowl
  8. step 8 :Installing the Wiper Arms
    • Line up the passenger side wiper arm on the windshield
    • Fasten the two 14mm nuts onto the wiper arm
    • Line up the driver side wiper arm on its stud
    • Fasten the 14mm nut onto the stud
    • Push the cap onto the wiper stud
    • Close the hood

Tools needed for replacement

  • Materials, Fluids, and Supplies

    Copper Anti-Seize

  • Ratchets & Related

    Socket Extensions

    Torque Wrench


    1/2 Inch Breaker Bar

  • Screwdrivers & Related

    Flat Blade Screwdriver

  • Sockets - Metric

    14mm Socket

    10mm Socket

  • Specialty Tools

    O2 Sensor Socket

Installation Video
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Hi, I’m Mike from 1A Auto. We’ve been selling auto parts for over 30 years!

To remove the driver's side wiper arm, you leave the hood down, use a small flat blade screwdriver, and gently pry up in this plastic cap. Find the edge and pull it off. There’s a 14mm nut under here. Use a 14mm socket extension and ratchet. Loosen this up. Pull that off. We're going to lift up on the arm and now I'll wiggle it back and forth and it should come right off the wiper arm shaft.

Open the hood. We'll go inside. Pull the release. Find the safety latch. Release that. The prop rod is under the hood. It's got two positions: one position here and then a service position here. It opens further. Passenger side wiper arm has two mounting nuts. They're 14mm. I'm going to use a 14mm socket ratchet again. Loosen that one up and loosen this one up. You might need to hold the wiper arm. Thread it off. It popped right off with just the spring action of the wiper arm. Lift it off the windshield and put it aside.

To remove the side corner trim, this'll be the same on both sides, pry it up with a plastic prying tool. You can buy this at Once it's up, you can slide it out. Put it aside.

There's two push clips on both sides that need to be removed. Use a small flat bladed screw driver. Pry it up. Pull the clip out. If the center part comes out, that's okay. Just push it back in to reuse it.

The center cowl piece is clipped along the edges, and then it slides up under the window glass. We're going to unclip it and slide it out this way. Go underneath and push the clips in. That one's loose. Go ahead and find all the clips. It might be easier to use the plastic trim tool to push the clip in. Push it up. Slide it from underneath the windshield. I think this one clipped back in. Yep. It did. Make sure these stay clipped out. Put that aside.

Unplug the wiper motor. The lock, the clip, is underneath the bottom. Squeeze it up. Pull the connector off. Wiring harness should be clipped into here. Somebody's had it apart before, so the clips are a little bit broken, but you'll have to pry this clip out of here. You'll have to either slide this off, or cut the electrical tape. Be careful not to cut the wires. Somebody's already had this apart. It'll come off here. There should be a clip here. It's missing, and then there's this clip here. And we just get the wiring harness out of the way.

There's a ten millimeter bolt here, one here, and then one here and here. That's holding the wiper transmission to the car. We'll use a ten millimeter socket, extension and ratchet. Remove these bolts. We'll lift the wiper transmission out of the car. It's sitting on a stud, just under here. So, we'll pull that off.

We need to remove the lower cowl panel. There's nine 10 millimeter bolts holding it in place. We'll need to remove all these bolts and then slide it out of the engine compartment. Use a 10 millimeter socket, extension, and ratchet. We'll need clearance, so we need to remove this bracket. It's two 10 millimeter bolts. Life it out of the engine compartment. Flop these down and over. Myself clearance.

Front O2 sensor is located at the read of the engine at the bottom of the exhaust manifold just before the catalytic converted. Follow the wire over. Connector is located right there at the back of the engine. Before we remove the O2 sensor from the exhaust we need to unplug it from the harness, so we're going to follow the wire from it sitting in this little guide to keep it away from things. We'll pop it out. Follow it over to the connector. It's hard to see because it's down behind the engine, but you can just make it out where it is. You're going to have to push the lock to the body side of the connector and then separate it out. Going to bend this wire guide out of the way so we have more room to work and I'll just bend it back when I'm done. There it is. We'll spray some rust penetrant to try to help remove the O2 sensor. Again, this O2 sensor socket, you can put a 3/8ths drive. Slide over the O2 sensor. I got it loose but I need to keep moving it so we can see. There it is. There's our O2 sensor.

We're going to reuse our O2 sensor, since it was working fine. We just wanted to show you how to take it out, but you do want to make sure you put some anti-seize on here. Copper works the best for exhaust stuff, it's high heat. Don't get it on the sensor tip. Try to get it just on the threads. Sometimes a brand new oxygen sensor will come with anti-seize already on it. If it doesn't, just add your own. Reinstall this into the exhaust. Thread it in as far as I can go by hand. Tighten this up. We'll tighten it just enough you'll feel the gasket crush on a new one. Since this one is used it'll go in a little bit. Make it tight. That should be good there. Just don't want it to leak exhaust. Then we can plug the connector back in. So we'll plug the connector back in. Keyed, it'll only go in one way. Click when it locks into place, and that wire holder that I bent out of the way, will bend back roughly where it was before. Clip the wire into there. The O2 sensor is replaced.

We've got our lower part of the cowl panel, the steel piece. These little air guides are folded over so they'll fit under the wind shield. Slide it into place. Start reinstalling the bolts. I'll just go along and start them all by hand, and then I can go back with a socket and ratchet and tighten them all. Shut that door. Snap it in place. When they get tight I'll stop. Clip this little door back. Tighten this one up. To install the support bracket, see the little tab that fits in there. This bolt caught here first.

Reinstall the wiper transmission. So, this little pin here, is going to go into this rubber grommet up here. Push it up into place, push it into that rubber grommet. Oops. That wants to pop out, so, let's see. Take it off and then push it on to here. Then, we can hook it in this way, just like that. Line it up with the mounting holes. Get our bolts. Get this one started. Start the other ones. Tighten these all up. Feel them get tight and then I'll stop.

Reinstall the harness for the wiper motor. So, this clip was kind of broken, but it does go in here. There's a missing clip here. You'd clip it back into place. This goes through this opening here. This is normally clipped into here. Then, there's a final clip here. And then, of course, you plug it in. It's keyed, will only go in one way. It'll click when it locks in place.

The plastic upper cowl cover, it's got some little tabs here. They're going to slide underneath of the windshield, the edge of it. Then, clips in the front that will clip down in the middle. Get it in position. Put it over the wiper arms. You want to slide it up. Push it along the edge and slide it over the glass like that. Then, it will clip down into place. Place the push clips. Do that for both sides.

Clip these little corner pieces back in place. So that part will go underneath the windshield, and these will clip into the plastic here. Slide underneath, clip them in place. Do the same for both sides.

Put the passenger side wiper arm in place. There was a little dust line here where the wiper blade was, so I'll use that as a reference point. Right about there. There's some spring tension to this that's pushing it back up. I'll install the nuts. I'll just tighten these down until they get tight. I don't want to break off the studs off the wiper transmission.

I'll reinstall the driver's side wiper arm and blade. You could do this with the hood down or the hood up. It's all right. Just get it in place. Reinstall the nut. Tighten it up. If I feel it get tight, I'll stop. I don't want to break the stud off. And reinstall the cap. It just pushes into place.

Thanks for watching. Visit us at for quality auto parts, fast and free shipping, and the best customer service in the industry.

Tools needed for replacement:

    Materials, Fluids, and Supplies

  • Copper Anti-Seize

  • Ratchets & Related

  • Socket Extensions
  • Torque Wrench
  • Ratchet
  • 1/2 Inch Breaker Bar

  • Screwdrivers & Related

  • Flat Blade Screwdriver

  • Sockets - Metric

  • 14mm Socket
  • 10mm Socket

  • Specialty Tools

  • O2 Sensor Socket

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