P0A40 Drive Motor B Inverter

P0A40 indicates a Drive Motor B inverter fault. The controller detected a problem in the inverter electronics that control Motor B power conversion.

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 disconnect inverter or motor high-voltage cables without the correct disable, wait time, and voltage verification steps.

Useful checks before replacing parts

Review inverter temperature, phase current data, Motor B torque command, DC bus voltage, isolation status, freeze-frame load, and related motor or inverter codes.
Inspect inverter coolant flow, connector condition, low-voltage power and ground, high-voltage cable seating, service plug status, and signs of water intrusion.
Follow high-voltage diagnostic procedures to separate inverter faults from motor, resolver, current sensor, cooling, or wiring problems.

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.