Where is the oxygen sensor on a 2002 Mitsubishi Lancer?

Answer 1

There are 2 Oxygen sensors on the Lancer. The 1st one is in the exhaust manifold and the other is after the catalytic convertor. The sensor in the exhaust manifold if easy to change. Open your hood and look at the front of your engine, you will see a heat shield with a hole in it. In that hole is a plug with wires coming out that is the O2 sensor (upstream). Use a 12mm wrench or socket to take off the 4 bolts on the heat shield. Follow the wires to a connector and disconnect the wiring harness. Move the heat shield so that you can bring it straight up out of the car. Use a 22mm wrench to loosen the O2 sensor. Finish spinning the sensor and wiring harness out. Once it is out take it to the parts store with you. You want to make sure you get a replacement that has the wiring harness and connector on the end. Don't get the universal O2 sensor unless you like to rewire connectors. Installation is very easy. Spin the sensor in, use the wrench to make it snug. You don't need to use much pressure. Put the wiring harness through the hole on the heat shield and connect it to the old one was attached to. Install the 4 bolts on the heat shield, clean up your tools, close the hood and you are done.