When you clear your codes or disconnect your battery it resets all vehicle self-tests, the vehicle's computer must then gather enough data under different driving conditions to determine whether each test has passed or failed. When the vehicle hasn't yet determined the results of a test it will be displayed as "Not Complete" until the results are in.
Your vehicle gathers test data through a process called a "drive cycle" - different tests will have different drive cycles and typically they will be specific to your make/model of vehicle. Some basic steps you can take to get through your drive cycles include:
- Idle your vehicle in the driveway and allow it to get up to operating temperature
- Drive your vehicle around town in stop and go traffic
- Drive on the highway at different speeds, holding your speed as steady as possible for extended periods (at least a few minutes)