Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture Delphi "ES21251-12B1" - Not availablePEUGEOT - 306, 106, 206, Partner, 806; CITROËN - Xsara, Saxo; FIAT - Ulysse