The check engine light in a Toyota RAV4 can indicate various issues, ranging from minor to more serious. It is recommended to have the vehicle's onboard diagnostic system scanned to retrieve the specific trouble code(s) associated with the light. These codes can help identify the cause of the issue, which could be anything from a loose gas cap to a malfunctioning sensor or a more significant engine problem. Consulting the repair manual or seeking professional assistance can help diagnose and address the specific issue.