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P0AA9 Severity
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
The high voltage system uses a battery voltage isolation sensor inside the battery control module to monitor separation of the high and low voltage systems. If sensor fails, P0AA9 will set. The high voltage system may become disabled.
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OBD-II Code High voltage system may not operate is defined as a Hybrid Battery Voltage Isolation Sensor Circuit Low
The high voltage system uses a battery voltage isolation sensor inside the battery control module to monitor separation of the high and low voltage systems. If sensor fails, P0AA9 will set. The high voltage system may become disabled.