On April 10, 2018, NHTSA received a petition from Mr. Kevin Byrne (the Petitioner) requesting that the Agency ?undertake a defects investigation? of ?rust-related detachment of Isuzu Rodeo fuel tanks? (NHTSA ID 11091788). The Petitioner experienced a partial fuel tank detachment in his model year (MY) 2004 Isuzu Rodeo in July 2017. On May 23, 2018, ODI opened DP18-001 to evaluate the Petitioner?s request for a defect investigation. ODI sent information request letters to Isuzu and Honda requesting production, design history and field data related to fuel tank retention failures in MY 2001-2004 Isuzu Rodeo, MY 2002-2004 Isuzu Axiom and MY 2001-2002 Honda Passport vehicles equipped with the same fuel tank shield part number as the Petitioner?s vehicle (the ?subject vehicles?). ODI notes that Isuzu manufactured the subject Passport vehicles for Honda. Isuzu implemented a change to the tank shield corrosion protection system as a running change in early MY 2002 production. Isuzu and Honda sold approximately 172,000 subject vehicles in the United States. Fifty-eight (58) percent of the subject vehicles were produced prior to the shield change (99,000) and 42 percent after the change (73,000).ODI?s analysis of field data identified 19 incidents of partial fuel tank detachments in the subject vehicles. The incidents all occurred in states with high road salt usage in winter months (Salt States) and involved older vehicles beyond 10-years in service. On average, the failures occurred in the vehicle?s 13th year-in-service. Evidence of severe general corrosion in multiple undercarriage components was also noted in 13 of the 19 vehicles that experienced partial fuel tank detachments. None of the incidents resulted in fuel leakage or fire. Aside from the petitioner?s vehicle, ODI has not identified any other incidents of complete or partial fuel tank detachment in the MY 2002-2004 subject vehicles equipped with the modified retention shield.In addition, ODI reviewed 24 NHTSA co