Code Definition

P0AA1 — Hybrid battery positive contactor circuit stuck closed

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0AA1

P0AA1 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P0AA1 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0AA1 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

This DTC is set when the hybrid/EV control module commands the hybrid battery positive contactor to open, but the circuit remains closed. The system monitors voltage and current feedback to verify contactor status. If voltage remains present on the high-voltage output side when the contactor is commanded open, the control module interprets this as the contactor being stuck closed.

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