FUEL RAIL SYSTEM — The check engine light came on after only three days/156 miles! OnStar was contacted and a diagnostic was run indicating ‘The Engine and Transmission System is not performing as expected. An issue has been detected in the Fuel Management System used to maintain control and monitor fuel consumption.’ I took the vehicle back to the dealership and was advised that the fuel rail system needed to be replaced but the part(s) are not available and there is no projected date of arrival. NOTE: The vehicle has been sitting at the Service Center since December 28, 2024 awaiting necessary repairs.