Ford 2013 Flex Owner's Manual page 316

If you see any corrosion on the battery or terminals, remove the cables
from the terminals and clean with a wire brush. You can neutralize the
acid with a solution of baking soda and water.
It is recommended that the negative battery cable terminal be
disconnected from the battery if you plan to store your vehicle for an
extended period of time.
Battery relearn
Because your vehicle's engine is electronically controlled by a computer,
some control conditions are maintained by power from the battery. When
the battery is disconnected or a new battery is installed, the engine must
relearn its idle and fuel trim strategy for optimum driveability and
performance. To begin this process:
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift lever in P (Park), turn off all accessories and start
the engine.
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven to relearn the idle and fuel trim
strategy.
• Note: If you do not allow the engine to relearn its idle trim, the idle
quality of your vehicle may be adversely affected until the idle trim is
eventually relearned.
When the battery is disconnected or a new battery installed, the
transmission must relearn its adaptive strategy. As a result of this, the
transmission may shift firmly. This operation is considered normal and
will not affect function or durability of the transmission. Over time the
adaptive learning process will fully update transmission operation to its
optimum shift feel.
If the battery has been disconnected or a new battery has been installed,
the clock and the preset radio stations must be reset once the battery is
reconnected.
Always dispose of automotive batteries in a responsible manner. Follow
your local authorized standards for disposal. Call your local authorized
recycling center to find out more about recycling automotive batteries.
2013 Flex (471)
Owners Guide gf, 4th Printing, December 2012
USA (fus)
Maintenance 315