Ford 2009 Flex Owner's Manual page 317

Roadside Emergencies
3. Remove the jumper cable from the positive (+) terminal of the booster
vehicle's battery.
4. Remove the jumper cable from the positive (+) terminal of the
disabled vehicle's battery.
After the disabled vehicle has been started and the jumper cables
removed, allow it to idle for several minutes so the engine computer can
relearn its idle conditions.
317
2009 Flex (471)
Owners Guide, 2nd Printing
USA (fus)