How-To: Replacing Oxygen Sensors

[APN]

Not all oxygen sensors are the same. When buying an oxygen sensor, make sure you have once with the correct adapter for your car. Some years of first generation neons may have one of two connectors.

The first is a round connector, the second is a square one. The connections are not adaptable to each other, but if you happen to get a used one and do not want to spend that much extra money, you may just splice the connector onto the new sensor.

There are two ways you may personally approach removing the old upstream oxygen sensor.

The first one would be from inside the engine bay.

Upstream:

• Pop the hood and prop it open
  Disconnect the battery as always
  If you have the stock air box in there, you will have to remove the front of it along with the filter inside (if you wish you may remove the whole assembly)
  You should now be able to see the sensor on the right just below where the air box would be.
  Use an adjustable wrench and fit it snugly on the oxygen sensor
  Turn counter-clockwise until you get the first turn out of it
  Once the sensor is loose, you will probably be able to turn it the rest of the way by hand.
  Disconnect the wire connection just below where the oxygen sensor was mounted
  There are no seals or anything in there, so you may now insert the new sensor in the old sensors place
  Screw the new sensor in clockwise and tighten (make sure you do not over-tighten or strip it)
  Re-connect the sensors connection
  Re-connect your battery

You may also jack the car up and put it on stands to get at the upstream sensor from below the car.

Downstream:

• Prop the car up on stands and make sure they are sturdy and safe.
  Disconnect the battery as always
  A little farther back from the front tires, you should see a sensor sticking out of the exhaust pipe.
  Use an adjustable wrench and fit it snugly on the oxygen sensor
  Turn counter-clockwise until you get the first turn out of it
  Once the sensor is loose, you will probably be able to turn it the rest of the way by hand.
  Disconnect the wire connection and remove all mounts that the wire is held up with
  There are no seals or anything in there, so you may now insert the new sensor in the old sensors place
  Screw the new sensor in clockwise and tighten (make sure you do not over-tighten or strip it)
  Re-connect the sensors connection and wiring mounts
  Re-connect your battery

After all of this, you can turn the car on and let the computer re-learn everything.

If you do buy one with the wrong connection, return it or solder the old connection to the new sensor. When soldering, there will be a black, gray, and two white wires. The white wires are interchangeable, so don't worry about getting those mixed up. Black for black and gray for gray. once done soldering each wire, wrap each in electrical tape. When all of the wires are wrapped, you may wrap all wires together; Just make sure you do not have any exposed wires.

The wires are around 17 gauge.. The solder may not like to stick.. Just keep at it until you finish.. It's worth it.

Both the upstream and downstream sensors are the same and the only difference is the length of the wires.


If I missed anything in this how-to, please let me know.


Circular connection:

[DOHCRT]

If you do buy one with the wrong connection, return it or solder the old connection to the new sensor. When soldering, there will be a black, gray, and two white wires. The white wires are interchangeable, so don't worry about getting those mixed up. Black for black and gray for gray. once done soldering each wire, wrap each in electrical tape. When all of the wires are wrapped, you may wrap all wires together; Just make sure you do not have any exposed wires.

The wires are around 17 gauge.. The solder may not like to stick.. Just keep at it until you finish.. It's worth it.

Its not a good idea to solder the O2 sensor wires. The O2 sensor actually pulls a small amount of oxygen through the wires to compare it to exhaust oxygen. This is how all zirconium dioxide (narrow band) O2 sensors operate, as well as some wide band sensors. Some sensors may, however, have a breather hole on the side of the sensor body. Since the oxygen cannot travel through the solder, the O2 sensor will read the same atmospheric oxygen content all the time. You may or may not notice a difference in drivability, but it will slightly change the O2 sensors readings in some climates.

Instead of solder, use heat-shrinking butt connectors. These will seal the connection but allow the necessary flow of oxygen.