P0A77 Generator Inverter Voltage Sensor Circuit

P0A77 indicates a generator inverter voltage sensor circuit problem. The controller cannot trust voltage feedback used to monitor generator inverter operation.

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 generator inverter high-voltage circuits until the system is disabled and voltage is verified safe.

Useful checks before replacing parts

Compare generator inverter voltage sensor data with DC bus voltage, generator command, phase current, freeze-frame load, and related voltage or inverter codes.
Inspect voltage sensor wiring, low-voltage connector terminals, reference or ground circuits, water intrusion, shielding, and inverter connector condition.
Verify sensor plausibility through service-approved measurements or data comparisons before replacing generator inverter components.

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.