P0AA6 Hybrid Isolation Fault Australia

You sure don't need to be sad.
The problem could be from any of the HV systems ranging from the hybrid battery, inverter, compressor, orange cabling, etc.

You need to get a hybrid capable scantool, or a tech stream, to help you with diagnosis.

I wished I was in the same continent with you, to lend a helping hand.

Take everything easy, and the fault would be sorted out.

 

DTC P0AA6 is a high voltage ground fault. Any component in contact with the high voltage potentially could be at fault:
High voltage traction battery, inverter, transaxle, air conditioner compressor.

You need to go to your local Toyota dealer or a mechanic who specializes in Toyota hybrids so that the three-digit subcode beyond P0AA6 can be read. That subcode may yield a clue about what subsystem has the electrical ground fault. A DIY alternative is to obtain Mini VCI (Toyota Techstream clone) so you can retrieve the fault codes as well as a dealer tech is able to.

A temporary workaround is to disconnect the 12V battery for a few minutes. The car can be driven once after the battery is reconnected. However the problem should not be ignored as this constitutes a safety issue.

The most likely problem is that a battery module is leaking electrolyte which allows electricity to travel across the electrolyte to reach the metal battery case and hence vehicle body ground. If the battery case is opened up, that will allow inspection of the battery modules. If you see corrosion on the battery case floor that is evidence of an electrolyte leak.

Another possibility is the transaxle has a motor stator winding which is leaking electricity.

 

I definitely would NOT install a "reconditioned" battery. Install a new battery sourced from Toyota if that is the problem.

The correct way to assess a ground fault downstream from the high voltage battery is to use a "megger". This is an ohmmeter that uses high voltage to assess insulation resistance. You would disconnect the cabling from the item in question, and then use the megger to measure resistance.

For example, to test the transaxle, you would disconnect the high voltage cabling leading to MG1 and MG2. You would then use the megger to measure resistance from each of the 6 high voltage terminals to body ground. The spec is 10M ohms or greater.

 

This may help, I believe the theory is accurate for your model. Watch it a few times and try it. It's done by Luscious Garage. As expert as expert can get with Prius vehicles. Very reputable facility. One of the first steps is to clear the trouble code. If you don't have the proper scan tools to do that, you would need to just disconnect the 12v battery for a minute or two and then reconnect it. Putting the car to ignition-on mode would require two presses of the 'power' button with your foot NOT on the brake pedal. Going to ready mode would be one push of the power button with your foot ON the brake pedal.
Then, assuming the car goes into 'ready' use the shifter to place the car into neutral.

 

Basically, recon batteries are not lasting. Sometimes not even 6 months. They can be useful as a stop gap measure to give you time to save up for a new battery. It also depends on the person doing the recon work. Some are better than others, but inevitably no one can make a silk purse from a sow's ear. It is good that it has a 1 year warranty, because the chances are that you will need ti use it, maybe more than once.

PS, the situation might be slightly different in Australia, if there is still a reasonable supply of second-hand battery modules, which reconditioners will rely on to properly recondition the batteries.