On August 7, 2018, the Office of Defects Investigation (ODI) received a defect petition from Mr. Gary Weinreich alleging premature frame corrosion failure in model year (MY) 2002 - 2006 Toyota 4Runner vehicles. The petitioner based his request upon a corrosion-related front suspension failure he experienced in his MY 2005 Toyota 4Runner, a class action lawsuit settlement involving other Toyota products, and other complaints of underbody corrosion in Toyota 4Runner vehicles that he found in NHTSA?s online complaint database. The petitioner submitted a complaint to NHTSA documenting his experience (NHTSA ID 11098055). On August 17, 2018, ODI opened DP18-002 to evaluate the petitioner?s request. ODI?s evaluation included information provided by the petitioner regarding his vehicle, facts related to the class action lawsuit cited by the petitioner, and consumer complaint data received by NHTSA regarding underbody corrosion in third and fourth-generation Toyota 4Runner vehicles.The undercarriage of the petitioner?s vehicle exhibited severe corrosion damage indicative of seawater immersion. The vehicle?s service history shows that concerns with underbody corrosion were first noted by a Toyota dealer in a multi-point vehicle inspection performed on April 28, 2011. The invoice for that inspection noted ?severe and excessive amount of rust on the undercarriage and on the drive shaft transmission.? Two years later, on October 21, 2013, another multi-point inspection by a Toyota dealer observed further progression of underbody corrosion damage, noting: ?rust on shocks/struts and other components,? ?rust on exhaust system,? ?both splash shields severely rusted,? and ?undercarriage very rusty.? On July 17, 2017, approximately 10 months prior to experiencing the suspension failure incident, an independent repair facility performing routine oil change and brake maintenance informed the Petitioner of a concern with ?excessive frame corrosion? on his vehicle. The service history, se