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: Control valve body removal
On-Vehicle Removal
Warning
Using compressed air can cause dirt and other particles to fly
out, causing injury to the eyes. Wear protective eyes whenever using
compressed air.
Caution
Clean the transaxle exterior throughout with a steam cleaner or
cleaning solvents before removal ...
Mazda 6 Owners Manual: Pid/data monitor inspection
1. Connect the WDS or equivalent to the DLC-2.
2. Measure the PID value.
Note
Perform part inspection for the output device after PCM
inspection.
The PID/DATA MONITOR function monitors the calculated value of the
input/output signals in the PCM. Therefore, if a monitored value ...