I hear that noise all the time after I turn off my car.

 

Pg 24 of 2013 Owner's Manual

"Noise from under vehicle after turning off the engine (RX350)"
Approximately five hours after the engine is turned off, you may hear sound coming
from under the vehicle for several minutes. This is the sound of a fuel evaporation
leakage check and, it does not indicate a malfunction.

 

Non-hybrid RX350
When I first noticed it happening, I waited after I shut down my car to see if it continued or started later. In all cases, it started sometime later after the car shut down. Made two email inquiries to the Dealer with no response. Thank you
hitting the start button without foot on the break then cycle off, shuts it down

 

i never heard mine do this? and i have had it for three years now.

 

 

Any modern vehicle would likely have a dead battery if you leave it for 2 months and do not attach a battery tender. All modern vehicles have numerous computers and other electronics that have memory and constantly drain the battery.
It is not the fuel evaporation leakage check that drained your battery, it was not attaching a battery tender. Besides, fuel evaporation leakage test occurs once several hours after you shut off the car and would have no effect on the battery condition 2 months later.
You can get a battery tender on Amazon for under $40.

 

Aha! I heard that sound the other day in the garage and a) didn't know what it was and b) couldn't identify the exact source before it stopped. It would have been about five hours after the vehicle had been turned off, and I had located the sound somewhere in the corner of the garage where the rear of my RX was. I even unplugged the freezer in the garage to make sure it wasn't the compressor making the noise.

Here's a Youtube video of the sound as made by a 4Runner:

 

Hi, this has happened to me a few times now but this time I'd thought I'd post since my warranty is almost going to expire.

Once in a while, when I come to the car in the morning after overnight when the car was obviously off, I hear a barely audible compressor like noise from the rear of the car and it sounds like it's coming from underneath. Does anybody know what this could be? I have attached an audio recording of it just in case.

Please let me know what you think. Thanks

 

I could be totally wrong as I am relating this to a BMW I have.

it could be a leakage diagnostic pump. This little compressor pressurizes the fuel system to check for leaks. It only checks every so often. The BMW usually checks just after you turn off the car. Lexus may be different.

 

MrSuperman...This is normal...It's been discussed here many times because its a confounding situation. It's a pump that checks the evaporative fuel system somehow.
I don't have the details, maybe someone else has, but I'm just chiming in to let you know that the car is supposed to do that.
Ray A.

 

Totally normal. Nothing to worry about at all.

 

Thanks to all who replied.

 

Strange noise coming from the rear of the car after parking. Sounds kind of like a pump running. Maybe a little hum. If I start up and move a little in reverse it stops. Anyone know what it is?Hasn’t affected anything yet. Car has about 57k miles and was a certified used. Tia

 

Nothing to worry about, it's just the EVAP system doing a check.

 

Rx has various modes and one of them is what I call "awake mode" [my term for state other than "sleep" and "run"]. In this stage the vehicle gets ready and primed to get into run mode and is recognized by presence of key-fob in/near vehicle. In this mode there is constant drain from the 12v battery and what you hear is most likely the fuel pump priming the fuel pressure line and once the right pressure is reached, the pump cuts off. [in run mode the alternator provides the current].
Other than the pump various other things can happen like purge valves etc being activated.

Moral of the story if any is keep the key away from the vehicle when you park it [Don't leave the keys inside].

Salim