DIY: Change an Oxygen Sensor on an Eclipse

by Jeffrey Caldwell
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The oxygen sensor on a Mitsubishi Eclipse measures the amount of unburned oxygen in the exhaust and relays that information to the vehicle's engine control computer. The computer then uses that information to maximize fuel economy and reduce tailpipe emissions.


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The oxygen sensor on a Mitsubishi Eclipse is located at the end of the exhaust manifold or on the exhaust pipe that runs between the manifold and the catalytic converter. It looks like a spark plug with a wire or wires attached to the end. Four-cylinder models will usually have one oxygen sensor. V-6 and some turbo models may have a second sensor located behind the catalytic converter. The procedure for removing both sensors is the same.


Wait until the engine and exhaust system have completely cooled before attempting to service the oxygen sensor. The exhaust pipe can become extremely hot while the engine is running and may cause burns.

Follow the wire or wires connected to the end of the sensor and disconnect it from the exhaust manifold or pipe. You may need a special socket that can usually be borrowed at no cost from your local auto-parts store.


Begin by applying an anti-seize compound to both the thread on the oxygen sensor and the threads on the exhaust manifold or pipe. This will make the sensor easier to remove the next time. Thread the sensor into the manifold and tighten it. Then reconnect the sensor wiring connector to the harness from the vehicle. If you are replacing the sensor because the check-engine light came on, you will need to use a code scanner to reset the engine computer.

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