A defect petition (see DP19-002) was received July 23, 2019 alleging that the occupant classification system (OCS) sensor (mat) in model year (MY) 2011 Nissan Leaf vehicles is defective and affects the proper deployment of the passenger front air bag. The petitioner provided a list of potentially related NHTSA reports and noted a Nissan recall involving later MY Leaf vehicles with OCS defect. NHTSA is granting the petition and opening a preliminary evaluation in response, please see PE19-015.Since receiving the defect petition, the Office of Defects Investigation (ODI) has determined that the MY 2011 and 2012 Leaf share a common OCS design, both using the same sensor mat for passenger presence sensing. Starting in MY 2013, Leaf OCS was changed to a design using a different sensing system, one that did not use the mat present in prior model year, Nissan Leaf. While MY 2013-2016 Leaf vehicles were recalled for an OCS defect under recall 16V-244, a recall influenced by ODI investigation EA15-004, earlier MY Leaf vehicles were not included because they were not affected by the particular defect involved in that recall.ODI identified and reviewed 13 vehicle owner questionnaire (VOQ) reports in its database, one of which is a duplicate, involving MY 2011 and 2012 Leaf vehicles that allege a problem with the OCS. The VOQs indicate that an OCS warning light illuminated at which point the vehicle was diagnosed and it was determined the sensor mat was the cause of the OCS problem. Most of the VOQs also noted the high cost of repair, which apparently involves replacement of the passenger front seat, according to complainants. None of the VOQs allege a problem with the performance of the passenger air bag, an injury, or a fatality due to the failure of the OCS.During the evaluation of this petition, ODI did not request information from Nissan regarding the complaint data in its possession, and accordingly the manufacturer complaint counts shown above are marked as not applicable. ODI will request this information during the upcoming investigation.The ODI reports cited above can be reviewed at NHTSA.gov under the following identification (VOQ) numbers: 11234415, 11207486, 11196006, 11193208, 11180021, 11176324, 11172159, 11152569, 11123812, 11103556 (duplicate of 11180021), 11102456, 11101830, 11052546.