Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture BOSCH "0 258 017 371" - Not availableBMW - 3, 5, 1, X5, 7; AUDI - A4, A3; HYUNDAI - I30, IX35; CITROËN - C4, DS3