Nissan conducted safety recalls 08V-311 and 09V-431 to remedy leaking master cylinders on certain MY 2007 and 2008 Nissan Sentra vehicles.The recall populations were determined based on production changes to the master cylinder which were fully implemented into production on April 18, 2008.NHTSA utilized vehicle owner questionnaire (VOQ) reports and did not request field information from Nissan.ODI identified two MY 2008 Nissan Sentra VOQs including the petitioner?s vehicle, which were not covered by the recalls and reported a leaking master cylinder.Both of these incidents occurred 6 or more years into the service life of the vehicle.ODI also identified three VOQs which reported a leaking master cylinder after receiving the recall remedy.While one of these failures occurred within 36 months of the recall remedy, the other two occurred at a later time.ODI notes that the original recall addressed failures which occurred early in the life of the vehicle, typically during the first 36 months of service.Master cylinders are generally expected to experience wear and thus will display a finite service life.After a thorough review of the available data in NHTSA's VOQ database, the agency has not identified a trend that would call into question the scope or adequacy of Nissan's recalls.Accordingly, and in view of the need to allocate and prioritize NHTSA's limited resources to best accomplish the agency's safety mission, ODI is denying the petition.A detailed summary of ODI's analysis of this petition is available in the investigative file for this action, and will be published in the Federal Register also.The agency reserves the right to revise this assessment should future circumstances warrant.The VOQs cited above can be viewed at NHTSA.gov under the following reference numbers: 10299791 10330891 10449038 10567372 10638813 10805749 10839357