P0A78 Drive Motor A Inverter Performance

P0A78 points to Drive Motor A inverter performance. Motor A inverter response does not match commanded voltage, current, torque, or temperature behavior.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Hybrid / EV
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace the inverter before verifying cooling, sensor inputs, DC bus voltage, and high-voltage safety status.

Useful checks before replacing parts

Compare Motor A torque command, phase current, inverter voltage, inverter temperature, DC bus voltage, freeze-frame load, and related inverter codes.
Inspect inverter cooling flow, low-voltage power and ground, high-voltage cable seating, interlock status, connector sealing, and water intrusion evidence.
Follow high-voltage diagnostics to separate inverter performance from motor, current sensor, position sensor, cooling, or battery voltage faults.

Related OBD-II codes

These nearby hybrid / ev entries can help compare wording and fault area. They may share the same verification status as the source database.