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: Customer Assistance (Puerto Rico)
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Mazda 6 Owners Manual: On-board diagnostic test
DTCs Reading Procedure
1. Perform the necessary vehicle preparation and visual inspection.
2. Connect WDS or equivalent to the vehicle DLC-2 16-pin connector located as
shown in the figure.
3. Retrieve DTCs by WDS or equivalent.
Pending Trouble Code Access Procedure
1. Perform the necessary ...