P0AAB Hybrid/EV Battery Voltage System Isolation Sensor Circuit Intermittent

P0AAB indicates an intermittent hybrid or EV battery voltage system isolation sensor circuit fault. Isolation feedback becomes invalid only part of the time.

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 clear intermittent isolation sensor faults without checking water intrusion and connector retention.

Useful checks before replacing parts

Review freeze-frame data, humidity or water exposure, road vibration, ready-up events, contactor state, and related intermittent isolation codes.
Inspect connector pin fit, battery ECU terminals, harness flex points, water intrusion, corrosion, loose grounds, and recently disturbed high-voltage parts.
Monitor isolation sensor data through repeated ready-up and shutdown cycles to reproduce dropouts, spikes, or implausible shifts.

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.