P0AA6: the high-voltage battery has lost its electrical isolation
Hybrid and electric cars run their traction battery and motor at high voltage, kept electrically isolated from the rest of the car so a fault inside that system can't reach anything a person might touch. This code means the battery management system has measured that isolation and found it's dropped below what it expects a safe system to hold. It doesn't say where the isolation has broken down, only that it has.
You might notice
- A hybrid system warning light comes on, sometimes alongside the main engine warning light
- The car may refuse to start, or limit itself to a reduced-power mode
- traction battery
- — the high-voltage battery that stores the energy driving a hybrid or electric car's motor
- electrical isolation
- — keeping the high-voltage system electrically separate from the rest of the car, so a fault in it can't reach anything a person might touch
What this code means for driving
Stop driving
The high-voltage system has logged a fault.
Stop driving now — leave it where it is until a garage has checked it. If a high-voltage or hybrid system warning appears or the car loses drive, that's an emergency: pull over immediately.
High-voltage systems are lethal and need qualified equipment. We're keeping this one to a garage because of the danger, not because we're unsure what's wrong.
This is what P0AA6 means taken alone, and that part won't change no matter what else your scan turns up. What's actually causing it can still depend on the rest of your codes. Read it with your other codes.
What the code itself says
P0AA6 is a powertrain (engine, gearbox and drive system) code, and the 0 after the letter means it is a generic code with a standard meaning.
Grouped here as: Hybrid and electric drive — Hybrid and electric propulsion, including 48V mild hybrid networks. That grouping is ours, to help explain the code. The code's official family is the letter at the start.
This page is generic. Your car isn't.
A code on its own only tells you what the sensor saw, not what's actually wrong — and that changes next to your other codes. Read this one together with the rest of your scan and we'll work out what's really going on.
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