How to Test if an Oxygen Sensor is Good or Bad?

[LeKathryn]

Methods to test the condition of an oxygen sensor are: 1. Use a multimeter to check the resistance of the oxygen sensor (between the heater terminal and the ground terminal), which is generally between 4 to 40 ohms. 2. Measure its feedback voltage by connecting two wires from the oxygen sensor, then plugging back the connector and measuring the feedback voltage. The number of voltage changes within 10 seconds should generally exceed 8 times. 3. Observe the color of the oxygen sensor. Typically, the tip of the oxygen sensor is light gray in color. White, black, or brown colors indicate abnormalities. The function of the oxygen sensor is to determine whether there is excess oxygen in the exhaust gas after engine combustion, i.e., the oxygen content, and convert the oxygen content into a voltage signal transmitted to the engine computer, enabling the engine to achieve closed-loop control targeting the excess air factor.