How to Eliminate the Rear O2 Sensor

by Zyon Silket
luxury car - model toy car image by alma_sacra from

O2 sensors measure the mixture of oxygen and gas expelled from your vehicle. This helps the onboard computer diagnose weather your car runs properly and is within federal pollution regulations. When people modify their cars to gain horsepower, the O2 sensor usually tells the computer that the vehicle is outside regulation and the check engine light comes on. Some people eliminate the rear O2 sensor located directly in front of the catalytic converter to overcome the check engine light.

Step 1

Locate the exhaust manifold bolted to the side of the engine head on the driver's side of the motor. Follow the exhaust pipe (called the down tube) from the manifold to the large oval catalytic converter that bolts to the pipe. The O2 sensor has a green wire extending from it; the sensor is white and it looks almost like a spark plug.

Step 2

Trace the green wire to the wiring harness it connects to. It should be about 4 to 6 inches away from the O2 sensor.

Step 3

Disconnect the green wire from the wiring harness by pulling the plastic connector on the green wire off the harness.

Tie the green wire around another wire on the harness to prevent the wire from hanging and possibly falling onto the exhaust pipe.


  • You can remove the O2 sensor completely and replace it with a threaded bung (metal threaded cap) by turning the sensor out of the pipe with a wrench and then by threading the bung into the hole. However, this will automatically cause you to fail an inspection before technicians do their emissions testing because they will see the O2 sensor is missing. If your "check engine" light comes on after you disconnect the O2 sensor, you will also fail emissions testing. You should only disconnect the O2 sensor in a vehicle you intend to use for racing or off-road use.

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