What is the sensor/module on the driver's side engine bay? It is making a high pitched ringing even though it has been turned off for a few days. It is on the driver's between the fender and airbox

 

That looks like the "Intelligent Key warning buzzer (engine room)."

That "module" is what beeps when you open the doors/trunk using the exterior buttons. It also sounds if you shut the car off while you're still in gear (AT models) or if you walk away from the car (with key) and the car is still on.

As for why it is making a sound with car off, that I don't know...

 

Perfect, thank you!

I looked up the conditions that would make it buzz and those aren't met, so it is either corrosion in the buzzer's electronic or mice got to some wires. The module is only $20-30 used but at least now that I know what it is I was able to find the part number and get one ordered

 

Im having kind of the same problem so every time I connect the buzzer module it starts to make a high pitch beeping noise even if the car if on or off and won’t stop unless I unplug it and but when I have it plugged in and it makes the beeping noise it gets quieter every time I step on the brake but goes back to full volume as soon as I let go of the brake
does anyone know how to solve this problem?

 

I just bought a used module, however when it arrived I plugged in the original module and it stopped. I installed the used module anyways but never plugged it in wiring harness. I don't care about the buzzer and it's not worth taking the chance for me with having the buzzer going off all night and day again.