Is it safe to drive an 07 Prius with P0AA6 code (Voltage Isolation Fault) due to a bad transmission?

If this is a new thread about the same issue you raised here, it remains true that "due to a bad transmission" in your thread title is premature until a second INF code shows up (or equivalent further diagnosis is done).

Once the second subcode shows up, depending on what it is, then you'll know whether it's "due to transaxle failure" or "due to battery failure" or "due to inverter failure" or "due to air conditioner failure" or "due to wiring failure", and from there it will be clearer what repair is needed.

The car will generally allow you to do some driving, though you may have to reset the code to get it started again. Safe? There's judgment involved. Good idea to get the problem taken care of soon.

On the other hand, jumping into a repair, before knowing what to repair, might be too soon.

 

If you have a way of clearing codes, you can also look for old threads on a way you can do some location of the leak yourself through a sequence of steps:

If the code returns after some time with the car only ON, the leak is in the battery.

If the code doesn't return until you make the car READY, the leak is in the frame wire or inverter.

If the code doesn't return until you shift out of Park, the leak is in the transaxle.

If the code doesn't return until you turn on A/C, the leak is in the A/C.

Those are more or less the same steps the ECU is doing for you when it has already logged the 526 subcode and is deciding what second subcode to log.

There are some OBD2 readers (other than Techstream) that also can read the subcodes, or at least can be taught to read them. There should be some Gen 2 Prius PID definitions findable on the net that include the locations of the subcodes.

Repeatedly clearing the codes to keep driving might be part of why the dealer only saw the 526. Clearing the codes of course takes things back to square one, and then the car has to re-detect first that there is a leak (and set the 526), and then in a later drive cycle see that it has set 526 and do the extra work to set the second code.

 

I don't know that I've seen a specific report of that, but it stands to reason that it could be possible.

If you never manage to catch it with that second subcode, then your mechanic can just follow through the whole "P0AA6 with only 526" troubleshooting section of the repair manual, which will involve taking a bunch of things apart and testing them with a megger. Here, "any mechanic" might mean "any mechanic comfortable with hybrids", because others might just say "high voltage system? megger? nope, not me."

Even when the second subcode is available, a good mechanic will still work through the troubleshooting steps for that code, which will still involve some megger testing to confirm what's going on. What's good about the second code is that it lets you focus that testing on the identified one out of like five possible areas, so it saves you 80% of the troubleshooting work.

 

I’m dealing with a similar error code now !
Please let me know when you can read my message here so I can send more details if ok

 

This code is about high-voltage leakage somewhere in the car (the high-voltage system is supposed to be fully isolated from all the rest of the car). It does not have to be in the transmission (though it can be). It does not have to be in the battery (though it can be).

The best way to troubleshoot a P0AA6 is to use a scan tool that will also show you the detail code, 611, 612, 613, or 614, telling you where in the car to look for the leakage. When you search threads here about P0AA6, you will find a lot of them include a diagram with red, pink. blue, and green areas showing where in the car to be looking, for each of those different detail codes.

For example, the frame wire is part of the 614 area, so if you had 614, the frame wire would be one thing for you to check, and if you had one of the other codes, then it wouldn't.

If you can't get your hands on a scan tool that shows the detail codes, and can't get your car to someone who has one, you can also just start from the very top of the troubleshooting steps in the repair manual and go down each branch; it just takes longer that way. Some of the steps call for an instrument called a megohmmeter or megger. You will also find multiple threads here describing that (including important notes about safety).

Happy troubleshooting!