O2 Sensor replacement on 02-07 Subaru WRX/STi:
8.) Near the top and the middle section of the wire the goes between the sensor and the plug, you will most likely encounter a couple of zip ties. You will want to cut them so you can pull the wire from the engine bay down to where the sensor is located.
9.) At this point you can either choose to leave the plug/wire connected to the sensor or you can cut it to make it a little bit easier to remove the sensor. I chose to leave it connected just in case the new sensor did not fix the CEL I was getting. You will want to put the O2 sensor removal socket on your extension and pull the plastic flap over to the right again. With the flap to the side, you would be able to fit the socket over the sensor without much of a problem. Go ahead and attach your ratchet.
10.)With a little bit of elbow grease, the O2 sensor should start to turn and eventually come right out of it’s threaded home.
11.) Your new O2 sensor should have come with a little packet of copper paste. Apply a bit of it to the threads of your sensor. This will help ensure that the next time you have to replace this little guy, it will be even easier to wrench out.
12.) Go ahead and put your new O2 sensor back in the bung that your removed the old one from. Screw it in by hand as far as it will go, making sure that it goes in relatively easy and you are not stripping any threads. When it is in as tight as you can get it by hand, trade up to your ratchet with the O2 socket on it and tighten it up. Don’t kill it, just get it nice and tight. If you want to be exact with how tight you get it, consult the manual for your car to get the torque spec. Also be careful that the wire coming from the sensor is out of the way! You don’t want to have to buy another sensor because you made a mistake and cut the wires. The next step is to thread the wire/plug back up to where it plugs in. Make sure you put a couple of new zip ties back approximately where you cut the old ones.
13.)Plug the new O2 sensor back in and put the cover back over it. Now put your wheel back on, tighten up your lug nuts and lower the car back down. Now you can either choose to clear the CEL that you were getting prior to replacing the sensor with an OBD2 Scanner, disconnecting the negative battery cable for a few seconds, or any other method your heart desires. You are done!
Tools Needed:
–O2 Sensor Removal Socket (7/8″ Deep Socket w/slit down side)
-19mm socket (depending on the size of your lug nuts)
-6″ socket extension
-ratchet
-flat head screw driver
-phillips head screwdriver
-Liquid Wrench/WD-40/PB Blaster/etc.
-car jack
-jack stands
Most importantly you will need a O2 Sensor Removal Socket:
Lisle 12100 Oxygen Sensor Socket
