2023 Lexus es300h ( hybrid system malfunction)
 

Hi everyone, I really need some advice.



This past Friday night, right after washing my 2023 Lexus ES300h with a pressure washer and wax, I had a major problem. About an hour later, I went to pick up a friend. I pulled over, helped him load the trunk, and when I got back inside, I suddenly heard a very loud fan noise. The car engine then shut off.



Right after, the dashboard went dark and I got a message saying “Key Not Detected.” I checked the remote battery but still:

• No A/C
• No power windows/locks/radio
• Another message showed: “Hybrid System Malfunction – Visit Your Dealer.”
• Two windows were down and I couldn’t roll them back up.

I had to tow the car to the Lexus dealership. Today (Monday), someone named John called me and said maybe I messed something up and blamed my dash cam. I explained that my dash cam has been installed for 5–6 months with zero issues. He still insisted it could be the cause and told me to go back to the dash cam installer.



This was very frustrating because I bought the car less than 6 months ago and it’s still under warranty. We argued and he said I need to speak to the service manager tomorrow.



Right now, I’m under a lot of stress. What if they say the warranty won’t cover it? What are my options?

• Should I agree to pay for repairs myself, or is that wrong?
• Is it smart to complain to Lexus corporate, or will that just take too long without good results?
• Has anyone had a similar experience?

Any advice or suggestions would really help. Thank you.

Pressure wash in what way? Exterior? Engine bay? Underside of the car? There was a recall on some Toyota/Lexus models for an issue with water getting into connectors resulting in corrosion of high voltage cables but your car isn't on that list.

I only used a pressure washer on the exterior — the body, front bumper, and windshield. I also sprayed from the front bumper area toward the radiator (to clean for airflow). I did not spray directly inside the engine bay.



The problem started about 60–90 minutes later. My dash cam has been installed for 5–6 months without any issues, so blaming it for a hybrid system failure doesn’t make sense. A dash cam is a low-voltage accessory and cannot damage the hybrid system — that suggestion is unrealistic.



This really looks more like water intrusion into an electrical connector or sensor.

Are there any code(s) listed on the work order? Blaming the dashcam is lazy on the part of Lexus. Maybe your 12 volt battery is dying.

No, the 12-volt battery is fine — we already checked it with a meter.



I believe there’s a good chance that water entered somewhere in the electrical system (engine bay, hybrid battery ventilation, or wiring).



My question is: if the Lexus service department refuses to fix my car under warranty, what should be my next step?

• Should I just pay out of pocket?
• Or is it better to call the corporate office and open a case?

Depends what they want for the repair did they give any estimate? Corporate is not going to help you. FYI this problem might go away on its own as the water evaporates but given this happened once it could easily happen again. First step is knowing what code(s) are stored otherwise you're in the dark.

Double post

You need a better explanation from the dealer of why the dash cam caused the problem. Saying maybe is not an answer and they should tell you what the problem is. Go there in person and talk with main technician and let him explain it to you. If the installers of cam left an opening for water intrusion that is a problem. Let us know what you ultimately find out.

Any luck from the Service Manager? The advice in this thread is good, you need diagnostic codes from the dealer. Did the dashcam installer use fuse taps or cut into the wire harness? Seems unlikely it's a dashcam issue since it's been working for so long, but sometimes the fuse taps can work loose. I would hope the dealer would have at least inspected the hardwire installation in the fuse block.

Can you describe in more detail how you were spraying into the front of the car, were you directing the spray into the radiator fins? It's odd how you noticed the fan running loud right before the malfunction.

Wait for an actual diagnosis rather than hear random theories from a random worker. You should be able to spray water anywhere at any angle at any part on the exterior of the car and it should not be an issue. i would've just left out any comments about a car wash--may as well have just been driving in the rain. if it's a legitimate issue with the car, the dealer would be more than happy to bill lexus for the labor hours. so i'm sure they'll find it.

Sounds to me like dealer has stopped any further diagnostic work since was told to carry back to cam installer. It could be a massive amount of money if Lexus denies claim.

I experienced something similar with my '23 300h about four months ago while driving through a torrential downpour. It makes me wonder if there's actually a manufacturing issue with connectors seals that allows water intrusion too easily. In my case, two fault codes were stored:P0572 – Brake Switch "A" Circuit Low & C1425 – ABS Open in Stop Switch Circuit. All the dashboard warning lights came on, and even got a "Hybrid Battery Critically Low" message. Despite that, the car drove normally. I read & cleared the codes myself before taking it to the dealer, so they reported "no issues found".

That said, I agree with all others, if a CEL was triggered, the dealer should be able to provide a specific diagnostic explanation. I’d recommend calling them to request details on the issue and sharing it here; so more knowledgeable members might be able to help further.

^^^ This could be, maybe they chose not to investigate further due to the presence of an aftermarket part. If you're willing to get into the legal territory, the Magnuson-Moss Warranty Act, makes it illegal for a manufacturer or dealer to void a product's warranty simply because an aftermarket part was installed, or because routine maintenance was performed by someone other than the dealer. However, if they can demonstrate that the aftermarket part or service directly caused the issue or malfunction, then unfortunately, you're out of luck.

Your car is under Lexus warranty. Go to a different dealership if you’re not having luck.

Do not offer to pay for any repairs.

That is the infamous "cablegate" fiasco on the RAV4 Hybrid. I don't think it impacted any other cars, it was corrosion in a High Voltage rear cable connector.

I pressure wash all the engines, including hybrids without any issues.
They are very well isolated.