So I've done a few searches for this sound coming from the engine and fixing my SES and im not too sure what to do. So I got my codes pulled for my SES and it's codes 420 and 430 so I've Been reading and I read this can be caused by a vacuum leak. Taking this into account I noticed my car doing a weird sound so I'm wondering if it's a leak causing the codes. So I've recorded a video capturing the sound my car is making. Hopefully it's good enough for u guys to tell what it is and if it's normal. If u listen closely you will hear a hissing sound. Hopefully the wind isn't too bad and you can hear the hiss fine.


(just uploaded the video, so it may not be the best quality yet)

 

Did you check the hoses in the engine bay for any visable leaks? If all else fails, most repair shops have professional fog machines that are used to find the source of leaks.

 

Just did some more troubleshooting and I found out that I can hear the sound on both sides of the car.
I tried switching gears a few times and one time the sound went away briefly after I put the car in reverse, once I put the car back into Drive and drove for 5 seconds the hissing sound came back. Another thing I noticed is that when I change gears the sound changes pitches as you can hear in the video.
It kind of sounds like a belt rubbing the wrong way or something.
I recorded another video, hopefully it's a bit clearer.

 

If you can hear the sound that well from outside the car with the hood closed it must be pretty loud. Follow the noise until you find it. If it's not coming from the engine then it's gotta be an exhaust leak. If it is coming from the engine then you need to pop the hood and listen the best you can to where it's coming from.

 

I'm gonna try and follow the sound tonight, I feel it's from the engine, I'll let you guys know.