What does code P0AA4 mean?

Q: What does code P0AA4 mean?

Hybrid/EV Battery Negative Contactor Circuit Stuck Closed. P0AA4 means the hybrid or electric vehicle battery pack's negative contactor has been commanded open by the battery control module, but the circuit still shows continuity or voltage on the load side, so the computer has detected a stuck-closed condition. The main negative switch that is supposed to isolate the high-voltage battery cannot be confirmed as open, which is a serious safety and isolation fault.

DTC codes / P0Axx · Hybrid propulsion / P0AA4

P0AA4Hybrid/EV Battery Negative Contactor Circuit Stuck Closed

P0AA4 means the hybrid or electric vehicle battery pack's negative contactor has been commanded open by the battery control module, but the circuit still shows continuity or voltage on the load side, so the computer has detected a stuck-closed condition. The main negative switch that is supposed to isolate the high-voltage battery cannot be confirmed as open, which is a serious safety and isolation fault.

SystemPowertrain

Code typeGeneric (all makes)

SeverityHigh

Fix difficultyProfessional

AreaHybrid propulsion

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.