Mercedes, the supplier and an outside lab analyzed the sunroofs and learned how the supplier had changed the process of the primer application several times, including having changed the drying time for the bonding agent.
In November 2019, the automaker determined the supplier reduced the drying time of the primer to two minutes from more than five minutes.
Mercedes ordered the December 2019 recall but vehicles continued to suffer from detached sunroof panels.
A driver may get advance notice before the sunroof flies away if they see loose components or hears too much wind noise from the sunroof.
More than 10,000 of the recalled Mercedes vehicles are in Canada.
Mercedes expects to mail sunroof recall letters Feb. 21, and dealerships will replace the sunroof panels if necessary.
Vehicle owners with questions should call 800-367-6372.
Abby Andrews