OEM DETROIT NOX SENSOR A0111531628 for DD5/DD8 AFTERTREATMENT SYSTEMS This is not an aftermarket part, it is OEM. These units are OEM "take-offs", they are brand new and unused but do not come in Detroit / Mercedes retail packaging. We buy complete units from Detroit / Mercedes and then break them down so that we can sell the pieces individually. Due to this, there may be paint marks or minor cosmetic blemishes, but we assure you they are brand new and genuine.