P0AA1 Hybrid Battery Pack Temperature Sensor B Circuit Range/Performance

P0AA1 points to hybrid battery pack temperature sensor B range or performance. Sensor B reports a value that is present but not plausible.

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 battery modules before checking sensor B plausibility and cooling airflow.

Useful checks before replacing parts

Compare sensor B temperature with other pack sensors, intake air temperature, cooling fan speed, pack current, freeze-frame load, and related temperature codes.
Inspect airflow restrictions, sensor mounting, connector fit, corrosion, water intrusion, harness damage, and battery ECU ground quality.
Monitor temperature response during cooling fan operation and changing pack load to identify lag, offset, or sudden jumps.

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.