Before working on any sort of electrical component in the car, it's a good idea to disconnect the negative terminal on the battery. Use a 10mm hex socket to loosen the connector around the negative terminal (it's the one on the right, if you're on the passenger side of the vehicle) and position it securely where it won't come in contact with the terminal while you're working.

To better reach the sensor, you can remove the engine cover. Pull up on the rear corners and it should snap off fairly easily. Remove the two air intakes - A and B, below - that connect to the cover (they just slide off) and then pull the cover off completely. Place it aside for later.

The sensor is located on the crankshaft and flywheel housing just behind the engine, on the driver's side. A small, L-shaped metal shield just behind it protects it from the heat of the exhaust.

There are two possible methods to remove the sensor. Try the easy way first, and if that fails, you'll have to do it the hard way.

Atop the connector, just behind the nub where the wire is attached, is a black plastic tab. The connector is secured in place around the sensor by the tab. Attempt to remove the sensor by depressing the tab (again, the part closest to you, not to the housing the sensor is attached to) while pulling the connector off. If you're lucky, the tab will depress enough to allow you to remove the connector. Don't pull too hard - if the tab is properly depressed, the connector should slide off without much effort.

If thumb pressure isn't cutting it, you can try using a pair of needle-nosed pliers to depress the connector. Be very careful, as it's possible to mangle or destroy the tab by doing this. It happened to me, and I ended up having to do this the hard way.

If you were successful in removing the connector (go you!), the rest of the job is straightforward. The single bolt holding the sensor in place on the underside should now be visible. You'll need an E8 female torx socket to remove it, using either a 1/4" drive socket wrench with an extension, or a 1/4" drive screwdriver. Be very careful to not lose the bolt!

If, like me, you were completely unsuccessful in removing the wire connector atop the sensor, don't despair. There's another option available to you, albeit one that requires a bit more patience and muscle power.

You'll need to loosen the two bolts connecting the heat shield to the bell housing - marked A and B in the image below (note that B is just out of frame). Both require an E14 female torx socket, and are unfortunately positioned in a way that requires some finesse to access.

To remove bolt A, be patient and take it slow. Try to position the socket wrench (or breaker bar, if necessary) in such a way to give you as much room to torque as possible. You may need a small extension or two to make it work.

To remove bolt B, I had better success by attacking it from the passenger side. It's a bit of a reach, but you have much more room to torque the wrench than bolt A. A breaker bar made this bolt the easier of the two by far.

Remember, you don't need to remove the bolts completely. Just loosen them enough to slide the head shield away from the sensor.

It's smooth sailing from here. Slide the heat shield away from the sensor, and use an E8 socket attached to a 1/4" drive socket wrench and extension, or a 1/4" drive screwdriver, to remove the bolt on the underside of the sensor. Take it slow, as it may require some patience and rotation of the socket to get it snug on the bolt. With the wire connector in the way, you're almost entirely going by feel.

Whether you've managed to remove the bolt the easy or hard way, you can now lift the sensor out of the hole in the housing. Make sure you recover the bolt immediately and don't let it drop down to somewhere you can't reach!

If you removed it the hard way, the wire should give you enough slack to pull the wiring connector into easy reach to remove it from the sensor. You can use a flat heat screwdriver to pry up the plastic piece that locks it in place, opposite the tab on the end. Just be careful to not damage it!

Whew! Now the fun part. Once the old sensor is disconnected from the wiring connector, you can take the new one and install it in the hole in the housing where the old one sat. Make sure the hole for the bolt aligns with the bolt hole in the housing. Ensure it's fit as far as it'll go in the housing before continuing.

If you want to be extra careful to not lose the bolt, you can take a length of sewing string and tie one end around the bolt. If it drops somewhere you can't reach, you'll at least have a length of string attached to it you can use to recover it. Thread the bolt through the hole in the sensor and tighten it with the E8 socket and wrench or screwdriver. If the string is still attached, you can yank on it to snap it off.

Reattach the wire connector around the new sensor. Make sure it snaps into place and the locking tab is snugly secured.

If you had to remove the sensor the hard way, be sure to tighten the two bolts holding the heat shield in place. Again, take it slow, and you can move to the passenger side of the car to access the higher of the two.

Reattach the engine cover over the engine. You'll notice four large black rubber knobs protruding from each corner - these are the points where the cover snaps onto. Make sure it's fit snugly and installed correctly over the throttle body in the back. Reattach the two air intakes as well.

Reattach the negative battery terminal. Make sure the bolt is tightened using a 10mm socket.