Operation of a vehicle that includes an autonomous operating system including an on-board map database includes operating in a travel lane employing a lane keeping control system and an adaptive cruise control system and monitoring a plurality of lane reference markers. Periodically, parameters are determined, including a first lateral offset for the vehicle based upon a forward-monitoring sensor and one of the lane reference markers, and a second lateral offset for the vehicle based upon a GPS sensor and the map database. A difference and an associated variance are determined, and an error in the map database is determined when the variance is greater than a threshold variance. The vehicle operator is alerted to actively control the vehicle based upon the detected error in the map database.