P0A8D: Low electrical supply during starting or i-stop restart

P0A8D identifies a low-voltage power-module condition. Mazda's SKYACTIV-G procedure evaluates several different starting-related measurements, so the code should not be reduced to one battery voltage taken with the engine stopped.

Four paths to the same DTC

The page lists battery voltage of 7.25 V or less during i-stop restart, DC-DC converter terminal voltage of 6 V or less during that restart, PCM terminal voltage of 6.2 V or less during engine starting, or excessive calculated battery internal resistance. The resistance limit is not published on this page.

These alternatives explain why the measurement location and timing matter. A battery reading can differ from the supply actually reaching the converter or PCM. Mazda inhibits i-stop engine stopping and identifies possible failure to start, stalling or failure to restart as voltage falls.

Distinguish a weak battery from bad information

The procedure considers current-sensor fault P058A and communication-related faults before relying on the reported battery condition. It then tests the battery and checks the battery, current-sensor, PCM and converter connections. The converter supply circuit is evaluated for an open or short to ground.

BATT_CUR and VPWR are the listed diagnostic data items. Repair confirmation includes engine starting and the specified battery-condition/i-stop initialization. Keep the captured starting event with the repair record; a healthy-looking voltage after the event does not disprove the original voltage collapse.

Documented application

Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; PCM (SKYACTIV-G). Verify exact vehicle specification; this is a Mazda application example. Mazda factory diagnostic page, mirrored by CHARM.