Does a Damaged Rear Oxygen Sensor Cause Increased Fuel Consumption?
2 Answers
A damaged rear oxygen sensor can lead to increased fuel consumption in a car, but the impact on fuel consumption is not significant, as its primary function is to monitor the purification efficiency of the three-way catalytic converter. A faulty oxygen sensor can increase vehicle emissions, causing the exhaust pollution to exceed standards. Additionally, a damaged oxygen sensor may prompt the engine control unit (ECU) to increase fuel injection, affecting the air-fuel ratio and potentially leading to higher fuel consumption. Below are details about the rear oxygen sensor: 1. Cars typically have two oxygen sensors: a front oxygen sensor and a rear oxygen sensor. The front sensor is usually installed on the exhaust manifold, while the rear sensor is located behind the three-way catalytic converter. 2. The primary role of the front oxygen sensor is feedback—it detects the oxygen content in the exhaust gases produced after combustion in the cylinders. Based on the oxygen level, the front sensor sends electrical signals to the ECU, which uses this information to adjust the air-fuel mixture. If the front oxygen sensor fails, it cannot provide accurate oxygen concentration readings. 3. The rear oxygen sensor mainly checks the filtration efficiency of the three-way catalytic converter. If the rear sensor is damaged, the car cannot determine whether the catalytic converter is functioning properly, preventing appropriate corrective actions. 4. As a critical component of the electronic fuel injection system, the oxygen sensor plays a vital role in ensuring proper engine operation and effective emission control. If the oxygen sensor or its connecting circuits malfunction, it can not only lead to excessive emissions but also worsen engine performance, resulting in symptoms such as stalling at idle, irregular engine operation, and reduced power.
A faulty rear oxygen sensor will definitely increase fuel consumption! Last time my car's fuel consumption suddenly spiked to 11 liters per 100km, and the mechanic found out it was due to a failed rear O2 sensor. This component specifically monitors the working condition of the catalytic converter. If the data is inaccurate, the ECU will improperly adjust the fuel injection. Black smoke from the exhaust pipe and poor acceleration are common symptoms, and sometimes the check engine light doesn't even come on. I initially replaced it with an aftermarket part costing over 300 yuan, but it failed again within six months. Later I gritted my teeth and bought an OEM part, and my fuel consumption immediately dropped back to 8.5L/100km. I recommend fixing it as soon as possible - otherwise the extra fuel cost could add up to the price of a new sensor.
