What are the symptoms of a faulty front oxygen sensor in a car?
3 Answers
Once the oxygen sensor or its connecting circuit malfunctions, it will not only cause excessive emissions but also deteriorate engine performance, leading to various issues such as stalling at idle and irregular engine operation. Below is a relevant introduction: 1. Oxygen Sensor: In engines equipped with a three-way catalytic converter to reduce exhaust pollution, the oxygen sensor is an essential component. Since the purification capability of the three-way catalyst for CO, HC, and NOx drops sharply when 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. 2. Oxygen Sensor Signal Voltage: The signal voltage of the oxygen sensor, as the most direct data reflecting the air-fuel ratio condition, is a crucial reference in fault diagnosis. In closed-loop operation, the working voltage of the oxygen sensor typically ranges from 0.1 to 0.9V. Usually, maintenance personnel use an oscilloscope to test or read the corresponding data stream with an electronic control diagnostic tool.
I've driven for over a decade and encountered faulty front oxygen sensors twice. The most obvious symptom was sudden fuel consumption spikes – where a full tank previously lasted 500 km, it barely reached 400 km later. The power delivery became sluggish too; even flooring the accelerator during uphill climbs couldn't muster proper strength. That glaring yellow check engine light on the dashboard was particularly annoying, accompanied by exhaust fumes smelling strongly like burnt rubber mixed with gasoline. During cold starts, the engine shook violently as if having convulsions, with black smoke puffing from the tailpipe. The mechanic scanned trouble code P0134, indicating weak sensor signals, and everything returned to normal after replacement. My advice: don't ignore these warning signs – get it checked early for peace of mind.
Last month, my car's check engine light came on, and after checking, I found out the front oxygen sensor was faulty. The most noticeable effect was the throttle response becoming significantly sluggish—I always seemed to lag behind others when starting from a red light. What hurt the most was the increased frequency of refueling; the same commute route now cost me an extra 200 yuan per month in gas. The exhaust pipe occasionally made popping sounds, and a sour, unpleasant odor lingered in the garage. The tachometer needle also behaved oddly, fluctuating between 800 and 1,200 RPM at idle. Using a mobile app to test the emissions, I discovered the hydrocarbon levels were over three times the standard limit. Later, I noticed the sensor connector was caked with oil sludge. Cleaning it temporarily restored normal function, but ultimately, replacing the sensor with a brand-new one was the only permanent fix.
