Nissan Pathfinder Lambda Oxygen Sensors Available Here. Do you want to make sure your vehicle is operating as efficiently as possible? Lambda oxygen sensors or O2 sensors as they are also known, precisely measure the air/fuel ratio in you vehicle's exhaust gases. They then feed this information back to the ECU which in turn adjusts the amount air and fuel being fed into the combustion chambers. What does this mean for you? Well, a faulty Lambda oxygen sensor could cause your engine to consume more fuel and produce more emissions, often resulting in an MOT/NCT test failure and poor running performance. At MicksGarage.com we stock a number of brands of O2 sensors to ensure we offer you the best choice.