What are the symptoms of a faulty front oxygen sensor?
2 Answers
When the front oxygen sensor fails, the ECU cannot obtain information about the oxygen concentration in the exhaust pipe, and thus cannot perform feedback control on the mixture concentration. This leads to increased engine fuel consumption and exhaust pollution, and the engine may exhibit symptoms such as unstable idle, misfire, and surging. Extended content: 1. The main function of the front oxygen sensor is feedback. Simply put, it detects the oxygen content in the exhaust gas produced after the combustion of the cylinder's air-fuel mixture. Generally, a high oxygen content indicates a lean mixture, while a low oxygen content indicates a rich mixture. The front oxygen sensor transmits different electrical signals to the ECU based on the oxygen content, allowing the ECU to adjust the mixture accordingly. 2. The exhaust gas produced after combustion in the car must be purified by the three-way catalytic converter before being discharged. The rear oxygen sensor detects the oxygen content in the purified exhaust gas and feeds it back to the ECU. The computer then compares the data from the front oxygen sensor. If the data from the front and rear oxygen sensors are the same, it can be concluded that the three-way catalytic converter has failed.
A faulty front oxygen sensor can cause a lot of trouble. I experienced this firsthand while driving. First, fuel consumption skyrocketed to ridiculous levels—normally a full tank would last 500 kilometers, but once it failed, it dropped to around 400, forcing frequent gas station visits. The engine also became unstable, shaking noticeably at red lights or idle, sometimes even stalling. The check engine light is a clear warning, but sometimes issues arise even without the light turning on. Exhaust emissions were abnormal too, with black smoke from the tailpipe or strange odors. Performance-wise, acceleration felt sluggish, especially when climbing hills. These symptoms make daily driving both frustrating and unsafe, so don’t delay—get it checked and replaced at a repair shop ASAP. Delaying repairs can also damage the catalytic converter, leading to even bigger expenses.
