Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture NTK "9358" - Not availableAUDI - A4, A6, A3, TT, S6; BMW - 3, 5; MAZDA - 6 (GG, GY); ALFA ROMEO - 156, Spider