How to Change an Oxygen Sensor in a Mitsubishi Lancer

by Christian Killian
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The oxygen or O2 sensor in your Mitsubishi Lancer is a vital part of the engine management system. The O2 sensor reads the percentage of oxygen in the exhaust and sends that info to the car's PCM or computer. The PCM uses the information to adjust the air/fuel ratio by altering the fuel flow from the fuel injectors. Changing the O2 sensor is not complicated, but you will need a socket designed for installing and removing it. You can get the socket at most auto parts stores.

Step 1

Raise the front end of your Lancer off the ground with a jack and support it with jack stands so you can safety work under it. Be sure you are on flat ground so the car stays still while you work.

Step 2

Locate the catalytic converter under your car. It is in front of the muffler near the front of the exhaust system. The O2 sensor will be right in front of it or right behind it, depending on which engine you have in your car.

Step 3

Disconnect the wiring harness connector for the O2 sensor by depressing the locking tab and sliding the connectors apart. You can leave the connector coming from the wiring harness hanging; you will connect the new sensor to it shortly.

Step 4

Remove the O2 sensor from the exhaust pipe using an O2 sensor socket and a ratchet. Turn the sensor counter-clockwise until the sensor is free.

Step 5

Insert the new sensor into the pipe and turn it clockwise to tighten it with the socket and ratchet. Connect the new O2 sensor to the wiring harness by plugging the pig tail into the wiring harness connector. Make sure it locks into the connector.

Step 6

Lift the front of the car with a jack and remove the jack stands. Slowly lower the car to the ground, then start it to ensure it is running properly.

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