Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Calorstat by Vernet "LS140020" - Not availableAUDI - A4, A3, TT, A6, A5; MAZDA - MX-5 (NB); ALFA ROMEO - 159, 156