A low level of electrolyte fluid will cause the battery to discharge quickly.

Inspect the electrolyte level at least once a week. If it is low, remove the caps and add enough distilled water to bring the level between the upper and lower level (illustration).
Do not overfill.
Examine the specific gravity of the electrolyte with a hydrometer, especially during cold weather. If it is low, recharge the battery.
Battery Maintenance
Battery RechargingMazda 6 Owners Manual: Service cautions
HANDLING INSUFFICIENT REFRIGERANT LEVEL
If an insufficient refrigerant level is detected at troubleshooting,
do not charge (add) the refrigerant. Because an accurate amount of
refrigerant cannot be determined from the pressure indicated on the manifold
gauge, never charge the refrigeran ...
Mazda 6 Owners Manual: Camshaft position (cmp) sensor inspection
Caution
When foreign material such as an iron chip is on the CMP sensor,
it can cause abnormal output from the sensor because of flux turbulence and
adversely affect the engine control. Be sure there is no foreign material on
the CMP sensor when replacing.
Note
Perform the follow ...