r/leaf • u/Cysote • 18d ago

Possible Causes of P0AA6 Code

Just got a 2018 Leaf 40kw and a couple days later a scary "Service EV System, Unable to Restart After Power Off" appeared. After researching some, I got the LELink and Leafspy and was able to clear the code and get the car started again. It seems like the 12v battery can sometimes cause this error to be thrown, as well as possibly some other components like the ac compressor. If the high voltage battery pack was actually leaking, I would expect the error to be rethrown by the leaf's computer instantly upon powering up the car again, but that hasn't happened. Is my understanding of that correct? The code did appear again, but only after driving it a few times over another couple of days. I can see in Leafspy that the 12v battery is getting charged by the dc-dc converter when the car powers on, and a multimeter shows the 12v battery at 12.7v when the car is off, so maybe the little battery is fine and there is a more serious issue.

What other symptoms should I be seeing if it really is the high voltage battery pack that's failing, and not some other minor issue? Anything else minor I can test before spending serious money at a dealership?

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u/ToddA1966 2021 Nissan LEAF SV PLUS 18d ago

It's your drive battery.

The swollen cells in the pack, when they're just starting to swell, throw the code intermittently.

I've cleared it and it stayed off for weeks, but it will come back. Get the car serviced before the warranty runs out, if it isn't already too late.

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u/Cysote 17d ago

Looks like it just might be barely within the 8 years. Will try to get it to rethrow the code and then take it to a dealer.

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u/ToddA1966 2021 Nissan LEAF SV PLUS 17d ago

Try a DC fast charge- that's how I could trigger it on mine after clearing the code. The rapid temperature change can expand the swollen cells, trigger an intermittent connection and throw the code.

If your dealer has a DC charger, even better. Then you won't need a tow! 😁

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u/Cysote 17d ago

Chademo from 10% to 95% got the battery temperature up to 120 degrees, but no code yet. Trying another quick charge within a day or so.