How to Determine if an Oxygen Sensor is Good or Bad?
2 Answers
Judging the condition of an oxygen sensor can be done by observing its color: if the tip is light gray, it indicates that the oxygen sensor is functioning normally; if the tip is white, it means the oxygen sensor has failed due to silicon contamination and is no longer effective. The automotive oxygen sensor is a critical feedback sensor in the fuel injection engine control system, playing a key role in controlling vehicle exhaust emissions, reducing environmental pollution, and improving the fuel combustion quality of the engine. The oxygen sensor uses a ceramic sensing element to measure the oxygen potential in various heating furnaces or exhaust pipes, calculates the corresponding oxygen concentration based on the chemical equilibrium principle, and serves as a measuring component to monitor and control the air-fuel ratio of combustion inside the furnace, ensuring product quality and compliance with exhaust emission standards.
With over a decade of experience in car repair, I often encounter oxygen sensor issues. To determine if it's faulty, first check the engine warning light—if it's on, there's a good chance. Use an OBD scanner to read error codes like P0130 or P0135, which directly point to sensor problems. Next, open the engine compartment, unplug the sensor connector, and measure the voltage. Normal values fluctuate continuously between 0.1 and 0.9 volts; if the multimeter shows a fixed 0 or 1 volt, the sensor is likely dead. Severe engine shaking at idle or a noticeable spike in fuel consumption are also signs—it's best to replace the sensor. Remember to visually inspect its appearance; if the sensor tip is discolored or heavily carbon-fouled, it indicates aging. A faulty sensor will cause excessive exhaust emissions, sluggish performance, and an unpleasant driving experience—address it promptly.
