On April 10, 2018, NHTSA received a petition from Mr. Kevin Byrne (the "Petitioner") requesting that the Agency -€śundertake a defects investigation-€ť of -€śrust-related detachment of Isuzu Rodeo fuel tanks-€ť (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 -€śsubject vehicles-€ť). 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 complaints alleging corrosion concerns with the fuel tank retention system in the subject vehicles that did not result in fuel tank detachment. Twenty-three (23) of these complaints involve subject vehicles built prior to the shield change. Like the vehicles reporting fuel tank detachments, these vehicles are also all from Salt States and, in most cases (20 of the 24 complaints), the vehicles also experienced severe corrosion concerns in other undercarriage components. Half (12 of the 24 complaints) of the vehicles show prior accident damage in their service histories.Based on these analyses, ODI has not identified evidence of a defect trend for premature corrosion-related fuel tank detachments in the MY 2004 Isuzu Rodeo or similarly equipped vehicles. The damage that may result in tank retention concerns appears to occur progressively over many years with ample opportunity for detection and repair. Furthermore, ODI has not identified any crashes, fires, injuries, or fuel leaks associated with fuel tank retention failures in a population of vehicles that currently range from 16 to 19 years old.Accordingly, the Agency is denying the petition.A summary of ODI-€™s analysis of this petition will be published in the Federal Register and is also available in the investigative file for this action.The NHTSA consumer complaints counted in the closing resume for DP18-001 can be reviewed at www.nhtsa.gov under the following ODI identification numbers (VOQs in parentheses denote duplicate records): Allegations of fuel tank retention failure: 11084098 (11091788), 10532845, 10486109. Allegations of fuel tank retention component corrosion: 11138931, 10992150, 10845523, 10824247 (10824308), 10597729, 10594770, 10558538, 10550870, 10544001, 10436344, 10424477,10399930, 10393933, 10393246, 10386578, 10374811, 10356153, 10339599, 10329133, 10322095, 10316008, 10296208, 10283640, 10275653.