2007 Prius P0AA6

This P0AA6 error is usually 90% a battery leaking issue. The quote of $3000, how do they intend to fix it? By refurbishing your battery? You know a new aftermarket battery is $1600 right? It's not refurbished, it's actually new

 

To help narrow down the fault you will need to know the INF code (aka subcode or secondary code) for DTC P0AA6.

Here is the workup for DTC P0AA6 (and or DTC P3009) : https://share.qclt.com/%E4%B8%B0%E7%94%B0%E6%99%AE%E7%91%9E%E6%96%AF%E5%8E%9F%E5%8E%82%E8%8B%B1%E6%96%87%E6%89%8B%E5%86%8Cpdf%E6%A0%BC%E5%BC%8F/Prius%20Service%20Manuals%202004/%E4%BF%AE%E7%90%86%E6%89%8B%E5%86%8C/04pruisr/05/21bpm/3009526.pdf

Once you know the INF code, this image will give you a better idea of the problem area and how to proceed :


Edit: typo

 

Asks the guys to provide you with a subcode of the isolation fault.

 

newpriusbatteries.com. It's an aftermarket battery, but many on here have bought this battery and it's been working for them. $1600 shipped to your door.

But I would still try to figure out where your problem is coming from before you dig into the battery. 90% battery leaking still leaves a 10% chance it's elsewhere in the car. A proper code reader would be able to give you sub codes, maybe a parts supplier (autozone, oreillys) type of places can read the codes for you?

 

Those guys aren't serious dude! Its either they usually outsourced to hybrid shops, or they are just not experienced. Why would a shop like that not have a code readers that could read subcodes?
Why don't you invest on a techstream software usually installed on an older laptop?

 

So if we get a sub 612 code with this you still think it is a HV battery issue and not a cable issue?
My scan says all modules are within spec. I did a visual inspection saw nothing. I will take it apart and check if I get proof I should be looking at the HV battery before anything else.

 

Did you read #3 posted by @SFO ?

 

Yes, I read post #3 along with about 100+ other related post. I picked this thread as it is the most current. As these vehicles get older we are bound to find situations that start deviating from the norms.

As mentioned in SFO's Post #3 it is important that when we post here to provide as much info as possible. In Post #3 SFO was saying that people don't post sub codes and thus it makes it really hard to help people and people do not post the correct info.

Since I just had this issue pop up figured it was a good time to demonstrate what is meant by providing adequate information, by not only providing main code, but the subcode, and then on top of that the scan data.

SFO also stated there 90% chance that any 526 code is a battery issue and only 10% a cable issue. Now with a 512 would that typically be a 100% battery issue even though the various others still say there is a large chance it is the cable between the Battery and Inverter? I also provided the scan data from techstream showing HV battery it "ok".

I am about to do a teardown of the battery but figured it was good to double-check I had not overlooked a smaller issue (loose cable) first.

 

This is a graph of my battery readings, which from my viewpoint do not show any bad cells.

Another time this is the reading I receive at a 53% SOC.


This is why I still question the 512 pointing to a bad battery. I found this link . Predictive battery failure analysis for the Prius Hybrid and will try reproducing this and charting the battery performace.

 

Ok

 

DTC P0AA6 points to a high voltage ground fault issue. This means that high voltage is leaking to the body. When the high voltage system is operating properly, both the negative and positive high voltage is isolated from the body.

The 612 info code points to the fault being within the high voltage battery, or the battery ECU, or the system main relays, the current limiting resistor, the associated cabling, etc.

Your Techstream screen images show that battery module pair voltages are relatively constant. That is nice, however that does not prove that the modules are OK. It is quite possible for one or more modules to be leaking electrolyte, which will provide an electrical path to the body ground.

If you open up the battery case and see corrosion on the battery case sheet metal below the battery modules, that will be indicative of where the electrolyte leak is coming from.

 

I went ahead and ordered some chargers figured I would check and recondition the battery while my car was out for maintenance. I am waiting on a megger to check for isolation issues in the wiring itself. I have already checked and see no leaks on the battery. Checking the load on the cells at 2 amp draw showed only 1 battery to be a different level than I expected, but everything in range.

I am left with checking the air filter as another individual said that was the issue. Even though I had replaced mine recently I check and it's dirty. I will be pulling the box out to make sure debris didn't get where they shouldn't have when I cleaned the air filter about 1 month ago with compressed air instead of replacing it.

 

Here is another test you can do: measure voltage from various battery module terminals to the sheet metal battery case bottom. If you can measure any voltage, that is proof you have a ground fault which is providing an electrical path to the battery case.

 

A P0aa6 fault can be driven by a number of areas, but a 612 subcode points to a HV battery issue. Most likely you have a battery module that is leaking and/or is causing a short to the case.

If removing the modules doesn’t give you a clue, I guess you can buy a megohmmeter and do some testing.

But in reality, you should just plan on buying another HV battery. New batteries for a Gen2 are priced quite well from Toyota.

 

Since you're inside the HV battery, be sure to also check each of the connectors and plugs/plugins for corrosion.

Pay special attention to the HV battery fan connection, as that can also corrode easily.

 

I ordered a megger and found the fault really quickly. The main fault was with the high voltage cable going from the battery to the inverter. At the inverter several years ago when the car was jumped wrong it blew out the fuse bus links next to the inverter. I nicely labeled all the cables I took off the inverter. Well, it seemed that when I reconnected it, one of the labels was crimped semi inside the HV cable coming from the battery. Just enough that over the years it degraded to the point it was creating a continuous grounding. It was easy enough to clean it up. And wow the code was gone.

Being happy with solving my problem I turned to pulling the battery pack for a good cleaning as recommended. I decided to move some middle cells to the edges and vise verse since during the charging etc I noticed they tended to get a bit hotter and had a little harder time in the middle area. Well when I bolted them down I first hand tightened and everything worked fine. Later when I went to put the pack in I torqued all the bolts/nuts to specs. But in the process (the bottom bolt) one cell grounded out . There is now ground to the threads on the bottom that wasn't there before. Is this common to happen if you over-torque the bottom screw?

 

I think you maybe snug off those studs without knowing.
I'd hbe preferred you torqued them all using the torque wrench than hand doing them at first before using the torque to spec.
How many of those modules are now grounding from the terminals? All or just the ones you've torqued initially to spec?

 

yeah used a torque wrench. These are not the bolts that connect the battery cable, THese are the ones that hold it to the frame of the battery case. I can't tell or see any damage around the encapsulated nut, but the battery cracked/or developed an internal leak after tightening to factory specs. I know these battery cases are subject to developing microcracks so it could just have been the slight twisting of the case in and out that made it open up.

Under visual inspection and bubble (liquid soap) I can't see any crack, but It must be there somewhere.