Audi A4/A6 Rear Oxygen Sensor 078906265T Direct Replacement Original OEM Number

For Audi A4, A6 and other models, the rear oxygen sensor can be directly replaced with original part number 078906265T. Core function is to monitor exhaust oxygen content and feed ECU to adjust air-fuel ratio, ensuring combustion efficiency. After installation, it can resolve high fuel consumption, excessive exhaust emissions, and engine warning light issues. If you experience sluggish acceleration, rough idle, or black smoke from the exhaust, sensor aging/failure is usually the cause; replacement can restore power and emissions compliance.