Hi, I have a 2010 Lexus RX 450h with 110,000 miles. A few weeks ago I got system message telling me to check the hybrid system. I took it to the nearest Lexus dealership and they told me it was a bad inverter water pump so I had them replace that. However, it didn’t fix it and I am still getting the message. They said the next step would be to change the inverter, which they quoted me at 7,000-8,000 for. There is no other Lexus specialists in my area and all the local mechanics are telling me they don’t work on hybrid systems.

Ive been looking online for a solution as I am semi mechanically inclined and can do some troubleshooting myself. I have an OBD reader and I pulled of the code P0A93. When researching it online it seems like it could be a couple things.

After they changed the pump I noticed that the fluid didn’t seem to be churning like say the power steering fluid would, but I not sure if it just doesn’t. They also added fluid above the full line so I was wondering if that would make a difference. I also checked a few of the fuses connected to the hybrid system including the pump and they all look good. I also located the vents for the hybrid system and they don’t seem to be covered or clogged.

I just want a second opinion since I have hard time believing its a 7,000 job.

Feel free to ask me any questions, I would greatly appreciate any help.

 

Do you know the code that popped the first time for which the dealership replaced the pump? There can be multiple problems but the dealership should not make you pay for their wrong diagnosis/un-needed repairs.

There are other hybrid and Evs, and inventor are some what common in them. Depending on where you are, expand your search. Lexus dealership is going to be the most expensive options and most likely they will swap components till the problem is solved.

Since you are dealing with lethal level of voltage [Charge], proper equipment and safety must be followed before tinkering with the system. The golden rule regarding DIY is know your limits. With that said, you can subscribe to Toyota TIS service and do the diagnosis and repairs.

Salim

 

Yes, it is the P0A93 code, which is the one that I am still seeing. Yeah, that's what I thought as well, but it wasn't the case.

I live in Hawaii so my options are very limited, I'm continuing to call around still though.

Yeah, definitely wasn't planning on going near the batteries. but thank you for the heads up.

 

So what was the story given by the dealership? Did they misdiagnose it and are they willing to assist/compensate?

The wires from the battery come to the inverter and the inverter takes the DC voltage and converts it into multiphase AC voltage for the motor(s). So you can disconnect the high voltage battery by its safety switch ... but don't let my description lower your guard.

Salim
PS: https://www.torquenews.com/8113/why-...3-trouble-code

 

You could try contacting and consulting with one of The Hybrid Shop locations in California. They are a nationwide franchise of hybrid specialists. They don't appear to have any in Hawaii.
https://www.thehybridshop.com/

 

They should have never changed the pump. The correct procedure for the fault code is to replace the inverter with converter assembly.

 

You could be 100% right, but do give us some insight.
The error as I understand is with the cooling, so it can be a problem with inverter with converter getting too hot, but it just might be the coolant loop [Prius had issues with the pump].

Salim

 

The dealership claimed that the pump was indeed bad, but only part of the problem and that multiple things must be fixed.

When I look up the code myself I get a variety of different things it could be not just the inverter.

• Faulty Inverter cooling system
• Inverter cooling system harness is open or shorted Inverter cooling system circuit poor electrical connection
• Faulty Water pump with motor assembly
• Faulty Cooling fan motor Faulty No. 2 cooling fan motor
• Faulty Inverter with converter assembly

I have been trying to do some troubleshooting myself, I checked the fuses that correspond to the hybrid system and they seem okay. I even unplugged the battery for a while just so the system could reset, I drove it around after that and it was working great the batteries were charging and the EV mode was working, but then 30 minutes later the message came back up.

Also, as mentioned in my first message when I look at the coolant reservoir it is not churning, is this normal? I would expect that I should see some movement.

 

If I was DIYing, I would focus on bullet item 2. Check the connectors to see if they are plugged in properly, look for pinched wires around the connector.
The link I sent mentions observing coolant movement.

Beyond that, find a hybrid tech.

Salim

 

Will do, thanks for the help. I’ll keep the thread updated if I figure anything out.

 

If it’s the coolant temperature, you will also get few other error codes that talks about temp sensor circuits, pump speed or pump performance.

the OP never mentioned these other error codes so one can assume the cooling system is fine.

 

Yes. that is correct just that error code is being thrown.

Do the inverter and converter typically need to be replaced hand and hand or can I isolate the issue and replace separately?

 

It’s not a unit that is supposed to be repaired. I have seen some attempt to repair it by visually inspecting any burnt resisters etc but it’s a long shot.

If you’re not comfortable with working on high voltage equipment I wouldn’t bother.

 

I would highly recommend a 2nd opinion from someplace like a local Hybrid shop outfit.
I haven't had that problem with my 2010 RX450, but several years back I had a Prius (my first hybrid) that had its hybrid batteries 'fail'. The dealership of course quoted me the $4,000 plus for a complete hybrid battery replacement and a 'whopping' 1-year warranty (LOL). I then found the local Hybrid Shop. Their equipment to test and service the battery pack was impressive, as was their knowledge, More importantly, they quoted me a 'restore and replace' service that would replace any failed units and provided a 2-year, unlimited miles warranty. It was a no-brainer choice for me -- and I never regretted it. The Prius worked great.
Notably, though, I realized that the Toyota techs weren't really well trained in servicing batteries at all. They simply followed the Toyota directions to recommend replacing the whole battery pack.
The moral: If you want a knowledgeable tech to truly diagnose your system, you need to go a 3rd party servicer. Toyota, Lexus or any dealer is not trained for nor expected to actually service the hybrid battery. Just replace it...

 

The statement is true for any hybrid or non-hybrid repair. At this time, dealers simply replace modules and never try to narrow down repair to the failing component. Not worth the time/compensation/inventory/training/retention and most of all customer satisfaction. Customer may not be happy paying higher price for repair, but they would be upset if they have to keep bringing the vehicle back to get the unit totally fixed ... at times the failed component has cause and effect. [There is a fine balance point, but keep in mind the dealer pass the cost of repair to the customer]

Salim