P0AA4

Hybrid/EV Battery Negative Contactor Circuit Stuck Closed

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$56–167 (est.)

Symptoms

The hybrid system does not turn off when the ignition is turned off
Warning messages on the dashboard
Reduced performance of the hybrid system
Problems with charging a high-voltage battery
The car may not switch to electric mode

Causes

Battery negative contactor fault
Problems in the contactor control circuit
Short circuit in wiring harness
Malfunction of the hybrid system control module
Corrosion or poor contact in connectors

How to Fix

Diagnostics of the contactor condition
Checking the control circuit and contactor power supply
Inspect the wiring harness for damage
Replacing the negative contactor if necessary
Reflashing or replacing the control module if necessary

Related codes

P0AA5 P0AA6 P0AA3