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  • DTC P0AA6 stands for “Hybrid Battery Voltage System Isolation Fault”
  • This code is logged when the PCM detects an isolation fault in the high-voltage system.
  • Possible causes include issues with the high-voltage battery and/or cables, as well as problems with the battery control module.
  • Common symptoms include lit warning lights, a battery that doesn’t charge, and vehicle startup issues.

Electric vehicles (EVs) have a low-voltage (LV) system and a high-voltage (HV) system. To prevent electrical issues and accidents during maintenance and repair, manufacturers deliberately separate the HV system from its low-voltage counterpart and the frame of the EV.

If the PCM detects an isolation fault in the high-voltage system of the hybrid EV, its diagnostics will log a P0AA6 code.

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What Does the P0AA6 Code Mean?

The diagnostic trouble code (DTC) P0AA6 indicates “Hybrid Battery Voltage System Isolation Fault.” It applies to electric vehicles, especially models with hybrid powertrains.

In both hybrid and all-electric vehicles, the high-voltage system is mounted on the body or chassis. It is a floating system–while its components are attached to the chassis, they do not rely on the chassis to electrically ground themselves.

electric vehicle cutaway model
In both hybrid and all-electric vehicles, the high-voltage system is mounted on the body or chassis.

Manufacturers design their EVs with a minimum level of resistance–also called electrical isolation– between the high-voltage system and the vehicle’s chassis.

If the high-voltage system wasn’t electrically isolated from the rest of the vehicle, its powerful current could make the vehicle unsafe.

The PCM regularly checks the high-voltage system. If it detects an isolation fault, it will set the generic code P0AA6.

Note: The definition of code P0AA6 can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

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What are the Common Causes of a Code P0AA6?

  • A fault with the high-voltage battery
  • Issues with the high-voltage cables
  • A problem with the high-voltage electronics or control system (e.g., a shorted traction motor, failed system main relay, faulty high-voltage A/C compressor, etc.)
  • An issue with the battery control module

What are the Common Symptoms of a Code P0AA6?

How to Diagnose the P0AA6 Code

Many vehicle makes and models can log a P0AA6 code. However, the exact circumstances that trigger the generic code can vary between vehicles. A diagnostic process that works in one case can fail to find any problem in another vehicle.

Bring your vehicle to a professional mechanic for a diagnostic test if you cannot do it yourself. Otherwise, you can go ahead and evaluate the issue yourself. To help you get started, here is a video that can give you an idea of what the process might involve:

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How to Fix the P0AA6 Code

Trying to clear a P0AA6 code can prove difficult if you lack the tools and know-how to test the high-voltage system. In most cases, it’s best to leave the job to professionals. If you are a DIYer with enough technical knowledge and hands-on experience who can test and replace your vehicle’s high-voltage system, it’s a good idea to refer to the vehicle’s repair manual or an online repair database.

About The Authors
Written By Automotive and Tech Writers

The Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Contact Center Manager and Technical Reviewer at

William “Bill” Guzenski has produced hundreds of how-to videos for the automotive community. He’s an ASE Certified Master Automobile Technician, and is affiliated with the Specialty Equipment Market Association (SEMA). He loves attending race events and car shows throughout the country, as well as traveling in his 40-foot motorhome, exploring abandoned mines and ghost towns.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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