Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture StartVOLT "VS-OS 2637" - Not availableBMW - 5, 3, 6, 7 (F01, F02, F03), X6, X5, Z4, 1, X3, X1; AUDI - A4, TT, A8