How to Test Whether an Oxygen Sensor is Good or Bad
2 Answers
To test whether an oxygen sensor is good or bad, you can unplug the oxygen sensor connector during maintenance and observe whether the engine fault disappears. Below is a detailed introduction to the oxygen sensor: 1. Overview of the oxygen sensor: The automotive oxygen sensor is a key sensing component in the electronically controlled fuel injection system. It is a critical part for controlling vehicle exhaust emissions, reducing environmental pollution caused by vehicles, and improving the fuel combustion quality of the car engine. Oxygen sensors are installed on the engine exhaust pipe. 2. Main functions of the oxygen sensor: The oxygen sensor enables the engine to obtain the optimal concentration of the air-fuel mixture, thereby reducing harmful gas emissions and saving fuel. The oxygen sensor measures whether there is excess oxygen in the exhaust after engine combustion and converts the oxygen content into a voltage signal transmitted to the engine computer, allowing the engine to achieve closed-loop control based on the excess air factor.
Checking the oxygen sensor isn't that complicated. I often use a multimeter to measure it myself. After warming up the car, lift it up, locate the spark plug-like sensor on the exhaust pipe, and measure the voltage of its signal wire with the multimeter. A normal sensor's output voltage should fluctuate between 0.1-0.9V, changing about 8 times every 10 seconds. If the voltage stays stuck at 0.45V or changes very slowly, it's most likely faulty. Sometimes I also use a diagnostic tool to check the data stream, focusing on the long-term fuel trim value. If the value is unusually high or low, it means the sensor isn't working properly. I remember last year a car's fuel consumption suddenly skyrocketed, and upon checking, the rear oxygen sensor was stuck at 0.6V. Replacing it fixed the issue immediately.
