Just purchased a 2013 450 and 2 weeks later inherited the P0AA6 526 and 613.

If I do indeed need to change the transaxle, does anyone have any specific information on if there are any differences in the transaxle throughout the years both RX and Highlander?

Some information shows the Highlander up to '19 might fit but the '16 up RX doesn't?

 

Welcome to CL. Don't throw parts at it based upon a code. How many miles are on it? Do you know the repair history? Is there any warranty?

Before just relying on codes to diagnose the transaxle (or power transfer unit as Toyota calls it) which rarely fails, you need further analysis by an independent hybrid shop as it is more likely the battery or some other related hybrid component as explained below: Do a Google search for hybrid car repair shops to find local places.

I found this data about those codes on a Prius forum:

From the 2010 DTC chart:

P0AA6-526
Hybrid Battery Voltage System Isolation Fault
- Hybrid vehicle transaxle assembly
- Generator cable
- Motor cable
- Inverter with converter assembly
- Frame wire
- No. 2 engine wire
- Hybrid battery junction block assembly
- Compressor with motor assembly
- HV battery
- Battery smart unit

P0AA6-613
Hybrid Battery Voltage System Isolation Fault
- Hybrid vehicle transaxle assembly
- Motor cable
- Generator cable
- Inverter with converter assembly

The way I read this the P0AA6 is the basic Hybrid Battery Voltage System Isolation Fault. This indicates a Ground Fault on the HV Battery system. The 526 Sub Code lists all of the devices on the HV Battery System.

The 613 Sub Codes seems to narrow this down to 4 possible devices, one of these being the Transaxle. You would need to test each of these circuits to determine which one has the Ground Fault.


So get a professional to do more diagnosis before shopping for a transaxle that is not likely to be the problem.
See this link for more code P0AA6 526 and 613 diagnosis information from a hybrid shop: https://hometownhybrids.com/trouble-...ic-code-p0aa6/

FYI
The Hollander database linked below is what many used auto parts dealers (a/k/a junkyards) use to determine what parts fit what models.
https://www.hollanderparts.com/

 

Very clean 144k
New 12v
No water intrusion in back, however did find moisture in passenger foot well and a bad windshield seal. Replaced windshield.

You provided great information and add to the hours of reading I have done, pointing out the benefit of this forum. I try to always educate myself which is why I feel so defeated inherenting this. Only after my purchase and registering it online with lexus.com was able to see that the previous owner had to have it towed to the dealer to be diagnosed as a faulty transaxle. They changed the fluid (I believe for the 1st time) I don't trust dealers as I feel they are lazy.
Currently I am looking for a great independent to do the proper tests without assumptions, but living in a smaller market choices are limited these days. When I do get it in with someone that knows what they're doing, I was trying to be prepared with ALL my options. If I have to replace it out of pocket it will be with something around the 60k mi range. I also wanted to be aware of any changes that would protect this from happening again.
My reading and concerns are with the MG1 having shorted due to what the dealer stated was (fine metal) in the fluid.

The day I bought it I did have an independent shop change the transaxle and differential fluid as precautionary (not knowing the history yet) and they said it looked good.

 

Hey.
So give u some information. I bought a 2010 RX 450 210k miles, same night on highway i got the isolation code and hybrid system overheat code.
I suggest you buy a obd2 scanner with Hybrid assistance installed on phone, to really drive hard on the road to see the transmission temperature while driving.
There is a theory for such kind of those transmission failure in Chinese Social Media, that its caused by MG2 Stator separation in the middle, that the separated stator whobble in the housing that damage the coil.
If the above theory apply to your vehicle, you would see some shinny metal mesh in the transmission oil. And the MG2 temperature will be higher than normal. Mine did that, and i end up with a used transmission from a 2013 car.
See my post: https://www.reddit.com/r/Lexus/comme...or_separation/ And: https://www.reddit.com/r/Toyota/comm...atf_killed_my/

 

I did do a scan, freeze frame does not indicate high temp. Right now I can clear the code. I does not return immediately but will almost for sure if I use EV mode. It does eventually return within a few days or so. I have learned how to cause it to trigger the hybrid display to stop and lock out EV around a certain corner in my neighborhood. Odd.
Each time I scan for codes I only get the 512. Have had it no start a couple times and still only the 512. Probably because my scanner is not good enough.
Good shops around me are hard to find, but i think I have found one that can do a proper diagnostic, I hope. I do have a suspicion the trans got hot at some point only because there is no other explanation.
It is either that or I cut my loss and move on.

 

I strongly get the Hybrid Assistance App, so that you can watch the temperature of MG1 and MG2. normally, MG1 will be higher than MG2, at around 80-90 F. If you saw MG2 is higher than MG1, that is a huge red flag.
Also you can drain some of the transmission fluid to check for metal mesh. Its very easy to see.
If your Tranmission meet above assumption, there is a fix in chinese social medai, that basically weld the separated Stator back. But however, Its not a topic here in the US, and very few people can do, so maybe only thing you can do is replace with another tranny.
Here is thescanner i use: https://a.co/d/09yh2OZZ The APP is free, See picture below:

 

Plus you have the about same condition as mine. I can clear the code that the code disappear for hours or days, and randomly came back somehow.