Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture NPS "DOX-2066" - Not availableTOYOTA - Aygo, Yaris; CITROËN - C1; PEUGEOT - 107; ALFA ROMEO - 156, 166; AUDI - A4, A3