What it means
The control module detects inadequate electrical isolation between the high-voltage system and vehicle chassis.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid battery management system monitors electrical isolation between high-voltage components and the vehicle chassis. P0AA6 sets when isolation falls below the system's acceptable level, which can result from damaged insulation or wiring, moisture or contamination in a high-voltage component, or a component fault.
Common causes
Most likely first.
- Damaged high-voltage wiring or insulation
- Moisture or contamination in a high-voltage component
- High-voltage component fault
Symptoms
- Hybrid-system warning light may illuminate
- Vehicle may limit or disable hybrid operation
- Reduced power or fuel economy
How to diagnose it
- Record freeze-frame information and hybrid-system warnings with a scan tool, and follow the manufacturer's safety procedure before any inspection.
- Without touching or opening high-voltage parts, visually check accessible high-voltage cable insulation and connectors for obvious damage or contamination.
- Check for signs of moisture or contamination around accessible high-voltage components, such as after water exposure, using the manufacturer's inspection procedure.
- Have the isolation fault measured and localized with the vehicle's prescribed high-voltage diagnostic process to distinguish wiring damage from a component fault.
- Confirm the isolation reading meets the manufacturer's specification after repairs before returning the vehicle to normal use.
Common fixes
- Repair or replace damaged high-voltage cable insulation or wiring using the vehicle's prescribed procedure.
- Correct moisture or contamination in a high-voltage component after identifying its source.
- Replace a confirmed faulty high-voltage component.
- Verify isolation meets the manufacturer's specification after repair.
Can I keep driving?
Do not touch high-voltage wiring or continue driving if the vehicle limits or disables hybrid operation, displays a stop warning, or behaves abnormally; move to a safe place and follow the vehicle's instructions. Arrange prompt qualified hybrid-system service because the fault involves electrical isolation from the chassis.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.