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How to Test a Wideband O2 Sensor

Updated February 21, 2017

Wideband oxygen sensors are used to increase the fuel to air ratio accuracy within the engine. Wideband O2 sensors are equipped with a five-wire system versus the traditional one or three wire sensor. The oxygen sensor measures the oxygen entering the engine at a specific time; the sensor relays this information to the engine computer, which allows the air to fuel mixture to be regulated. It's important to check the sensor if you notice your "Check Engine" light appear, or if your vehicle engine is running poorly.

Open the bonnet of the vehicle and locate the wideband oxygen sensor. The sensor is mounted on the exhaust manifold; refer to your repair manual for a diagram as location can vary by manufacturer or installer.

Disconnect the wideband wire harness; wideband harnesses have five wires instead of the traditional one or three-wire harness. Depress the side tabs and pull the harness out of the O2 sensor.

Clip the positive multimeter lead to the signal wire terminal on the sensor. The signal wire terminal is the third one in from the side (middle out of the five terminals). Clip the negative mulitmeter lead to a grounded point. A grounded point can be the negative battery terminal or the metal surface of the manifold or engine.

Set the multimeter to "DC Volts." Turn the engine on and allow the vehicle to idle for one minute. Monitor the mulitmeter; you should see a reading between 1 and 5 volts. If you are getting no reading; the sensor is faulty and should be replaced.

Things You'll Need

  • Multimeter
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About the Author

Johnathan Cronk is a freelance writer and began writing at the age of 18. Throughout his career he has specialized in sports, how-to and advice articles. He has also written sales pitches in the corporate setting since 2001. He studied business at Hudson Valley Community College before transferring to the State University of New York, Albany.