Symptoms of Faulty Front and Rear Oxygen Sensors?
2 Answers
Symptoms of faulty front and rear oxygen sensors are: 1. The malfunction indicator light turns on, and the engine shakes; 2. Increased fuel consumption with a pungent odor; 3. Unstable idle, sluggish acceleration, black smoke from the exhaust, and a popping sound. In engines that use a three-way catalytic converter to reduce exhaust pollution, the oxygen sensor is an essential component. Methods to check the oxygen sensor: 1. When the engine temperature is normal, disconnect the oxygen sensor's wiring connector and use an ohmmeter to measure the resistance between the sensor terminals; 2. When the engine reaches normal operating temperature and maintains idle speed, use a voltmeter to measure the output voltage of the oxygen sensor's signal terminal; 3. Observe the color of the oxygen sensor's tip: a black tip is caused by carbon buildup, a brown tip is caused by lead contamination, a white tip is caused by silicon contamination, and a light gray tip is the normal color of the oxygen sensor.
I've been driving for nearly twenty years, so let me explain the symptoms of failing oxygen sensors. The front sensor, located at the head of the exhaust pipe, measures exhaust oxygen levels and sends feedback to the ECU for fuel mixture adjustment. The rear sensor sits behind the catalytic converter to monitor emission efficiency. When they malfunction, the engine warning light (a small yellow flashing indicator) on the dashboard typically illuminates. Fuel consumption noticeably increases – where a full tank used to cover 500 km, it might drop to 400 km now, hitting your wallet hard. Performance-wise, acceleration becomes sluggish, feeling weak during hill climbs or overtaking, while idle RPM may fluctuate erratically, causing concern. Worse still, exhaust emissions exceed standards, guaranteed to fail environmental tests, sometimes accompanied by black smoke or odd odors from the tailpipe. Neglecting repairs long-term damages the catalytic converter, driving up repair costs. I recall severe highway vibrations once caused by a faulty rear sensor. At the first sign of trouble, visit a garage to read fault codes promptly – don’t delay. Replacing sensors is usually affordable and benefits both engine longevity and driving safety.
