On November 23, 2020, the Office of Defects Investigation (ODI) opened PE20021 to investigate allegations of inoperative Trimark THP 060-1650 door lock/latches originally equipped on model years (MY) 2015-2017 Class A and Class C motorhomes.ODI received forty-six Vehicle Owner-??s Questionnaires (VOQs) describing consumers being locked in or out of their vehicles.The door latch, containing a die-cast zinc plunger, was produced by Equality during calendar years 2014-2016. The die-cast may become porous and brittle over time and can break without warning, causing the vehicle owner to be unable to open the recreational vehicle door equipped with the latch.If the motorhome does not have any other doors such as some Class A models, occupants could be trapped inside, needing to climb out using the emergency exits. If locked out, owners would be unable to easily get in and retrieve children and pets. ODI analyzed the data provided by Trimark in response to its January 27, 2021 information request letter.Although an elevated failure rate was evident on a specific combination of plunger bolt, door lock/latch assembly and door, the data showed that most failures occurred within the first two years of service on the affected 2015-2017 vehicles.This data suggests that component failures generally would have already occurred.Further, ODI data reflects a downward trend in complaints after calendar year 2018 and for post- MY 2016 vehicles.This downward trend may be attributed Trimark's actions in 2016 such as changes in the manufacturing process of its zinc plunger component for the relevant population and its 2016 decision to switch to a steel plunger. In view of the nature of early-life failure, and failure rate trending downward for model years 2017 and newer, this Preliminary Evaluation (PE) is closed.? The closing of this investigation does not constitute a finding by NHTSA that a safety-related defect does not exist.The Agency reserves the right to take additional action if warranted by future circumstances. To review the ODI reports cited in the Closing Resume ODI Report Identification Number document, go to NHTSA.gov.