Oxygen, Lambda Sensor Exhaust Oxygen Sensor (O2 Sensor) Measures oxygen in the exhaust so the ECU can correct the air-fuel mixture RIDEX "3922L0425" - Not availableBMW - 3 (E46, WB), 5, 1, 6, 7; AUDI - A4, TT; MERCEDES-BENZ - CLK, C-Class T-Model