One problem related to tailgate has been reported for the 2018 Honda Odyssey. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2018 Honda Odyssey based on all problems reported for the 2018 Odyssey.
A water leak above the tailgate control module flooded it to the point that it operated erratically and would raise and lower the tailgate randomly or not work at all. I plan on replacing the module myself but will retain the old one. Anytime the entry or exit points on a vehicle open randomly cannot be a safe condition. The dealer charges $130 for any inspection or diagnostic so no I am not paying them to tell me something is broken. The vehicle currently is showing a "power tailgate problem" and a yellow box with "tailgate" in it on the dash display and is currently unresponsive to any input that would operate remote, tailgate buttons, and driver button. The power locking system is still operable. The odyessy forums clearly describe multiple occurrences of this failure and the culprit is a water leak in rear window or rear section of roof trim strip on the drivers side. My module did have water in it when I opened the plastic case it is contained in. Cleaning and drying it restored operation for about 3 days. Thanks for your help!.