Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Kawe "8845 50521" - Not availableAUDI - A4, A6, A3, TT, S6; MAZDA - Premacy, 323; BMW - 3, 1; ALFA ROMEO - 156, 159