Slight shudder and then triangle- P0A7a code- What is it?

In case anyone else is reading this, I think my problem is solved. My hybrid battery was going bad, and when I swapped it for a Nexcell lithium kit, the p0a7a has never happened since. It's been over 3 months and several thousand miles.
So, as mysterious as it is, I think this is not an inverter problem at all; it's a hybrid battery problem, which freaks out the inverter.

 

Generally, I expect each trouble code to mean exactly what the "detection condition" box in its repair manual section says it means (this is not the same as always meaning what many people think or say it means).

If the car is happier with the new battery and the code hasn't been back for a while, that's certainly good news, but I would still be cautious about inferring that the code doesn't mean what it says. It might be, instead, that there's an intermittent issue of the kind P0A7A reports, and it mostly shows up under higher generator loads that you were seeing more often when the battery was weak.

 

Interesting, yeah that makes sense to me. Hey, as long as it's not an issue anymore, I'm happy. Now to get my aftermarket cat to stop throwing P0420 and all my trouble codes will be resolved! Ordered an O2 sensor spacer which should hopefully do the trick.