How to Test an Oxygen Sensor?

[Spencer]

Oxygen Sensor Testing Method: The condition can be judged by observing its color: The normal color of the oxygen sensor tip is light gray; a black tip indicates carbon contamination; if the oxygen sensor tip appears reddish-brown, it suggests lead contamination. In engines equipped with a three-way catalytic converter to reduce exhaust emissions, the oxygen sensor is an essential component. Since the three-way catalyst's ability to purify CO, HC, and NOx drops sharply once the air-fuel ratio deviates from the theoretical value, an oxygen sensor is installed in the exhaust pipe to detect the oxygen concentration in the exhaust. It sends feedback signals to the ECU, which then adjusts the fuel injector's fuel delivery to maintain the air-fuel ratio near the theoretical value.