Hello All,

My 2006 RX400h has thrown a DTC P0AA6 and will not start.

I was able to read the DTC with a small bluetooth OBD2scanner - but it does not show the INF sub code(s).

Is there a way to read the INF code without a scanner? - perhaps from a hidden screen on the navigation unit?

Or are the INF codes only accessible with dealer tools like Techstream?

Thanks in advance!

 

Any Pros scanners that support OEM.

There are only six sub codes for P0AA6. INF526, 611, 612, 613, 614 AND 655. When I have a moment I'll show you how to check the basics.

 

Thanks Tammap,

Is there a specific scanner you would reccomend?

Before I buy another tool I'd like to be sure it will do what I need it to do.

I have an Xtool A30M, it does a bunch of things, including Freeze Frame data for the P0AA6 DTC, but does not show the INF codes.

On another forum I read that the Autel AP200 might give the INF codes - can anyone confirm that?

Thanks again!

 

I like this mid-level scanner, but It's a little too pricey for casual user.

You can call and talk to Jorge Menchu and get his advices. Jorge wrote some excellent articles for Motor magazine, read it when you have a chance!

https://www.aeswave.com/Autel-MaxiSY...et-p10102.html

https://www.aeswave.com/Articles-by-...Menchu-17.html

Can you elaborate more on your issues with P0AA6 and no start. I'm sure it didn't just suddenly happen.

Do you have a DVOM (multimeter)? You will need one.

Check and clean the battery cables; make sure it's super tight.

Make sure your battery voltage is ≥ 12.4 volts.

I suppose the READY light was never on and security light has stopped blinking. Have you tried to start your vehicle with a different key? Have you checked the following fuses 2, 3, 6,16, 30, 40, 41, 44, 45 and 56? I'm sure you did, but I have to ask.

Test the voltage at the AMD terminal; the terminal is under the + sign plastic cap in the main R/B. Connect the positive probe there and the negative probe to the ground. The voltage reading should be 12.2 -14.0 volts. Also inspect the AMD terminal for sign of looseness

Once you have checked all of the above then we can go to the next steps. If you have already done with all the above then we can start to check the relays. let me know.

 

Thanks again Tammap,

Yeah, that Autel ms906 unit is more than I need just now.

Regarding the P0AA6, here is some background:

First, the cabin heater has not worked for some time - suspected Aux Heater Pump failure. It hasn't been a problem in the warm weather. Otherwise A/C works fine.
The 12V battery was replaced in October last year, and a "Check Hybrid System" warning occurred at that time. I don't know if there was a P0AA6 or not, since replacing the battery cleared the warning.
(Voltage checked just now at 12.8V)
For the last 3-4 months the car has been parked outside, and driven only occasionally.
On cold days, my wife won't drive the car because of condensation on the windshield. Running the A/C will keep the windshield clear, but it is too cold for her.
I drove the car the other day, with the A/C on, and parked for a few hours, until it was good and cold out.
When I came back there was very heavy condensation on the inside of the windscreen.
This is when the current P0AA6 warning first occurred.
Remembering the previous occurrence (when the battery was replaced) I disconnected/reconnected the battery and was able to drive home - though the warning reappeared during the drive.
The next morning the car would not start until the battery was disconnected/reconnected. This is when I got the scanner out and read the P0AA6.
It has gone through a couple of iterations of this as I have moved the car around, and made room in the garage.
There are no apparent leaks, or musty smell, however the carpet is damp under the rear floor mats - haven't looked under the rear seats yet.
Currently the car is in the garage, floor mats out, and a space heater running, hoping to dry things out, while I seek a new scanner to read the INF codes.

In the meantime I have checked the items you suggested.

I do have a volt-ohm meter
Battery reads 12.8V, connections are tight, and fuses are all good.
Hopefully, once the INF code is obtained, it will indicate where to look for the voltage leakage.

Thanks again!

 

@mafogle I'm very certain that your sub code is INF 612. The water intrusion is compromising the HV battery area. It's affecting the HV relay assembly. Therefore you were able to start the vehicle with a battery reset (disconnected/reconnected)

Have you and your wife driven the vehicle through any flooded standing water?

If my memory serve me right, there was a TSB regarding water intrusion at the door hatch for Lexus RX vehicles. I'll try to find the TSB for you.

If you're mechanically inclined and handy at DIY, I could get you the service information to inspect the HV relay assembly to see if the HV relay is still ok with minimal corrosion. It might just need to dry out.

 

@tammap
Nope, no standing water, just been out in the weather since summer.

Good news is that the AP200 arrived this morning.

Better news, for the moment anyway, is that after a full 24 hrs of drying out, the P0AAA6 has not reappeared.

Unfortunately there are no DTC's in memory - so I cannot get the INF code - quite annoying.

The bad news is now the AP200 unit is stuck on the OBD2 connector and won't come off.

The unit has a window on the molded shield protecting the male pins, and it has latched onto the female connector on the vehicle, and won't let go.




For comparison, here is the XTool A30M

 

A couple of these tools should release the OBD reader from the OBD connector.

 

@mafogle The fault code P0AA6 not reappearing sounds promising but you are not out of the woods yet!

Indeed, there was a TSB regarding water leaks at the liftgate area affecting 2004 - 2009 Lexus RX 330, 350 and 400H. Check your VIN.

You need to water the back of the SUV and observe the seam above the upper back door strut mounting bracket (on both sides of the vehicle) for water. I have attached all the images.

If water is present, send the vehicle to a body shop (per Lexus TSB)

I'm sure you can try to DIY at home. You can apply some type of silicone to the area, wait until it is properly cured, then try the watering method again to see if that stops the water intrusion.

Also remove both rear quarter panel to see if there are any signs of water intrusion, and what damage has been done.

You still might have to access the HV battery area and determine if there is any water damage to the battery itself.

 

@tammap

Hey thanks, this is some good info. It looks like my vehicle is one of those effected.

I take it that the spot weld in figure 3 is a corrective action - I don't see any sign of a spot weld on my RX. There is some kind of sealant in the seam, it looks intact, no sign of cracks, but never can tell. when things warm up again I will perform the leak test as suggested.

In the meantime, I got the Autel OBB2 off of the connector using a plastic pry tool, the kind used to open cell phones.

Happy Holidays!

 

Happy Holidays! @mafogle and everyone here on CL!