P0AA6 Check Engine Light warning and code and Water Leakage by Trunk Door Stays and Damage to Hybrid Battery System on Lexus RX400h

Average mileage: 101,750 (50,000–183,000)
3 model years affected: 2006, 2007, 2008
5 people reported this problem
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Our Lexus displayed a check engine warning and P0AA6 Code and then immediately stopped working. Upon inspection at dealer, the entire bottom floor of the cabin (under the floor boards) was flooded without any visible water damage inside the cabin or any visible point of water entry. We were given an estimate of approximately $11,000 to repair because the entire hybrid battery system had to be replace, inverter and other components along with the interior carpet had to be ripped up and replaced in the process. It turns out water was entering from very small fractures in the seams by the trunk door stays. These are not visible to us unless you are trained to know to look there as Lexus mechanics have been trained. Upon researching this because to me this indicated there was a manufacturing defect if the seams do not stay sealed and over time separate, there are two TSB's specifically addressing this issue. L-SB-0019-09, issued March 10, 2009 and L-SB-0045-09, issued April 29, 2009. In order for a TSB to be issued Lexus has to receive a threshold number of complaints on this issue. Lexus then investigates and comes up with a solution to correct this problem. TSB's are part of a computer data base available to service technicians so they can look it up and determine what may be allowing water intrusion and how to repair. Apparently, there were enough complaints of flooding and it was determined these seals were not holding and allowing water to come in over a period of time. The problem is Lexus did not issue these TSB's until well after most of the covered vehicles (2004-2009 models of three different Lexus cars) were out of warranty. Lexus also chose not to tell its customers of the potential for the separation and magnitude of damage that can happen from this defect. The repair to seal the seams is only a few hundred dollars compared to the damage you may suffer, in the thousands of dollars, if the leak goes undetected until the hybrid system shorts out. There are no warnings and your vehicle can shut down abruptly with the potential of severe harm to you whenever water gets into an electrical system. Lexus really dropped the ball on this one but is benefitting greatly by having you over a barrel once the damage is done and you have to pay for the repairs. Lexus did immediately agree to cover the battery without a complaint from us. However, when we went to customer care and complained that Lexus knew of this defect and refused to do any preventative notification or recall we only received a token $600 more. I then went to corporate who flat out refused to help us and would not accept responsibility since the car was out of warranty. We did not want to put the claim through insurance since the car would then be labeled as water damaged/flooded and be of no value on a trade in/resale. We got stuck with a $4000 bill for damages that could have been prevented by a simple notice from Lexus advising of the potential for damage and suggesting we have the seams resealed. We would have gladly spent a couple hundred dollars in preventative care then face the damages we just had to assume. Anyone who has experienced this needs to complain to Lexus and voice their disappointment!
2007 Lexus RX400h 50,000 mi,
We have had terrible leakage problems. It started with flooding the floor on a number of occasions which became intolerably mildewed no matter how much we dried it. There was water accumulation in the doors as well. Lexus claimed it was due to clogged roof drains and we had to replace all the floor carpeting at a major cost. Subsequently the hatchback has had a leaking problem whenever it is opened after a rain. It leaks from the middle on the right side onto the floor of the cargo area. Lexus repaired it once, for thousands of dollars as they said they had to take it apart and put it back together to fix. Now it is happening again within months of the service. As you wrote, this seems to be a defect. Is there any way to get Lexus to acknowledge, and cover repair costs?
2006 Lexus RX400h 104,000 mi,
I had exactly the same problem. In my case the battery wasn't damaged but the relay and tray had to be replaced. Most of it was labor, getting at the hybrid battery required some amount of disassembly to get to the tray, which was flooded.