What are the causes of a rear oxygen sensor malfunction?
2 Answers
The causes of a rear oxygen sensor malfunction are: 1. The sensor is infected with a virus, causing system failure; 2. The catalytic converter malfunctions; 3. The sensor itself has quality issues, with a layer of substance covering its surface, causing slow response or failure; 4. There is carbon buildup or oil on the exterior of the sensor, or oil and dust have entered the interior. The oxygen sensor is a standard component in cars, typically consisting of a front and rear sensor. The front oxygen sensor is installed on the exhaust manifold, while the rear oxygen sensor is installed behind the three-way catalytic converter. The primary function of the rear oxygen sensor is to monitor the purification effectiveness of the three-way catalytic converter by measuring the oxygen content in the purified exhaust. A malfunctioning oxygen sensor can lead to unstable idling, resulting in insufficient engine power, sluggish acceleration, and black smoke from the exhaust. If these issues occur, the vehicle owner should promptly inspect and repair the sensor.
I've worked in auto repair shops for over 20 years and seen many cases of rear oxygen sensor failures. The most common reason is natural aging of the sensor itself - after 100,000+ kilometers of use, the internal ceramic components wear out and stop functioning. Secondly, contamination issues are quite troublesome, such as when engine oil or coolant leaks into the exhaust pipe and coats the sensor, blocking signals and causing false readings. Corroded or broken circuit connectors are also frequent problems, especially in northern winters where road de-icers corrode wiring. There's also a hidden cause - when engine combustion is incomplete and black smoke appears in the exhaust, severe carbon buildup can clog the sensor's pores. I recommend car owners conduct regular emission tests and immediately check the sensor if they notice increased fuel consumption, rather than waiting until the engine light comes on. During regular car washes, pay attention to cleaning exhaust system components to prevent oil buildup. When this part fails, it not only increases fuel consumption but may also lead to excessive emissions and potential fines.
