Volvo Car USA LLC and Volvo Car Canada LTD (Volvo) on behalf of Volvo Car Corporation, has decided to launch Service Action S29878 on certain model year 2017 - 2018 XC90, S90, V90, V90CC, XC60 vehicles. Volvo has identified that the lower flap in the capless unit that is located inside the fuel tank filler pipe, intermittently may not close completely after refueling. This could result in a Check Engine Light and Diagnostic Trouble Code ECM-P0044200.