P0E10: Low ISG supply voltage reported to the engine controller

P0E10 identifies generator inverter power supply A circuit low. In the documented Mazda M Hybrid application, the PCM records the code after the integrated starter generator reports its own P0E10.

Separate the report from the measurement

The factory PCM description is an ISG power-supply voltage decrease. It supplies no numerical voltage threshold, measurement duration or terminal test for this summary entry. Applying a conventional 12-volt alternator limit to it would therefore go beyond the source.

The immediate diagnostic distinction is which module holds the fault. Mazda's procedure reads the ISG directly and follows its DTC troubleshooting when an originating record is present. A code in the PCM only may instead be retained history. The manual explicitly recognizes that case, so an old engine-controller record should not be mistaken for proof of a currently low generator supply.

What the driver may notice indirectly

The listed protective actions inhibit conventional generation, i-stop, regeneration, motor assistance and non-generation control. They explain why more than one hybrid feature may become unavailable from a single electrical-supply report, without proving that each affected feature is defective.

Repair confirmation includes a key-on, engine-off self-test and another PCM inspection, with communication diagnosis if the fault persists. Keep the original snapshots and ISG records before erasing them. Any supply-circuit or generator work must use the applicable professional hybrid procedure; this summary page is a routing aid, not an internal power-electronics test specification.

Documented application

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