Denso Air and Fuel Ratio sensor is designed to detect the amount of the exhaust gas air and fuel ratio. It is constructed from durable material that is corrosion and abrasion resistant. This sensor features zirconia solid electrolyte integrated with alumina heater substrate which precicely controls the amount of oxygen concentration that flows into the diffusion layer to limit current flow. This sensor can easily be installed and ensures longevity.Porous PTFE filter allows atmospheric oxygen the enter the sensor without permitting water or engine contaminants to seep into the casing.