Region Letter: Certain 2011 - 2018 Model Year Sienna Vehicles Coverage for Certain Internal Functional Concerns of Certain Sliding Door Parts. Specific information for Region support is provided below. In our continuing efforts to ensure the best in customer satisfaction, and pursuant to a Sienna sliding door class action settlement, Toyota is announcing a Customer Confidence Program. The following information is provided to inform you and your staff of the program notification schedule and your degree of involvement.