DTC C1137: Reverse Gear Switch: Description
WARNING: This page is about a different car, the 2018 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.
This DTC sets when the ABS module receives an "invalid" message instead of the actual current transmission gear or when the reverse gear message indicates the transmission is in REVERSE when other stability control inputs received by the ABS module indicate the vehicle is moving forward.