Kia Optima: Checking the Coolant Level
WARNING - Removing Radiator Cap

Check the condition and connections of all cooling system hoses and heater hoses. Replace any swollen or deteriorated hoses.
The coolant level should be full in the radiator and between F (Full) and L (Low) on the coolant reservoir tank when the engine is cool.
Check the coolant level using the dipstick attached to the reservoir cap.

If the coolant level is low, add enough coolant to bring the level to F, but do not overfill. If frequent additions are required, see an authorized Kia dealer or another competent repair center for a cooling system inspection.
Engine Cooling System
Changing CoolantSeat Belt Buckle Switch (BS). Description and Operation
Description
The SRSCM shall monitor the status of the driver and front passenger seat belt buckle.
The SRSCM provides one pin each for the driver and front passenger seat belt buckle
status input ...
Rear Power Window + Seat Heater Switch
...
Battery recharging
Your vehicle has a maintenance-free,
calcium-based battery.
If the battery becomes discharged in a
short time (because, for example, the
headlights or interior lights were left on
while ...