P0A7B Boost Voltage System Isolation Fault

P0A7B indicates a boost voltage system isolation fault. The high-voltage boost system has detected insulation leakage or isolation below the expected threshold.

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 drive or service high-voltage components with an unresolved isolation fault until the safety procedure is followed.

Useful checks before replacing parts

Review isolation resistance data, boost voltage, battery pack voltage, inverter status, freeze-frame conditions, and related isolation or ground fault codes.
Inspect high-voltage cables, connectors, coolant intrusion, water damage, boost converter housing, service disconnect seating, and recently serviced components.
Follow manufacturer isolation test procedures to isolate whether leakage is in the battery, converter, inverter, motor, generator, or wiring.

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.