Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
Your car's battery has a special switch that helps it start. This switch is stuck and not working right, so the car might not start or run properly.
The P0AA5 code indicates that the circuit controlling the negative contactor of the hybrid or electric vehicle's battery is stuck open, preventing proper electrical flow.
The hybrid or electric vehicle's battery system uses contactors to connect and disconnect the high-voltage battery from the vehicle's electrical system. The negative contactor is responsible for completing the circuit on the negative side of the battery. If this contactor is stuck open, the circuit remains incomplete, and the vehicle cannot properly utilize the battery's power.
• Vehicle won't start
• Warning light on the dashboard
• Reduced or no power from the battery
• Faulty negative contactor
• Wiring issues in the contactor circuit
• Faulty battery control module
Contactor: A switch used to control high-voltage power.
Circuit: A complete path that allows electricity to flow.
• Check for any blown fuses related to the battery system.
• Inspect the wiring and connections to the negative contactor.
• Test the operation of the negative contactor using a multimeter.
• Replace the faulty negative contactor.
• Repair or replace damaged wiring in the contactor circuit.
• Replace the battery control module if necessary.
• Multimeter
• Wrench set
• Diagnostic scanner
$300 - $800
Moderate
• Toyota Prius
• Chevrolet Volt
• Nissan Leaf
• Regular maintenance checks of the battery system.
• Ensure all electrical connections are secure.
• Avoid exposure to extreme temperatures.
Electrical Circuit Issue
• Do not attempt to drive the vehicle until the issue is resolved.
• Consult with a professional mechanic for diagnosis and repair.
Check with your vehicle manufacturer for warranty coverage on hybrid/EV battery components.
This code is commonly associated with hybrid and electric vehicles that have been in service for several years, especially if maintenance has been neglected.
High – This issue can prevent the vehicle from operating properly and should be addressed immediately.
Driving with a malfunctioning battery system can lead to unexpected vehicle shutdowns and poses a safety risk.
• Vehicle in 'ON' mode
• Battery system engaged
The negative contactor is typically located near the high-voltage battery pack, often in a protective enclosure.
Q: What happens if I ignore this code?
A: Ignoring this code can lead to the vehicle not starting or shutting down unexpectedly, which can be dangerous.
Q: Can I fix this issue myself?
A: Due to the high-voltage components involved, it's recommended to have a professional mechanic handle the repair.
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