A connector position assurance device having multiple features for assuring a full coupling and locking of a female housing with a male housing in a connector system, such that the female housing and male housing are placed into a fully coupled and locked position when the connector position assurance device is moved from a pre-lock position to a full-lock position. When the connector position assurance device is at a full-lock position, a first member on the connector position assurance penetrates a window formed on the female housing, and at least one ledge extending from the connector position assurance device prevents a flexible member of the female housing from being moved downward, providing assurance that the female and male housings are fully coupled and locked together.