Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture RIDEX "3922L0032" - Not availablePEUGEOT - 306, 106, 406, 405, 206; CITROËN - Saxo, Xsara; OPEL - Vectra C, Signum