The suspension pulsation damper will cause a humming / buzzing noise when not working correctly.
See TSB Topic number LI32.50-P-048280 for more detailed information.
Not every thing I do is according to the strict guidelines of WIS, so use my directions at your own risk.
Jack up front end. Find the 2 bleed screws on the LF and RF next to the torque strut bushing and bleed the system. Make sure you have the car secure because you will lose all suspension pressure after this is done.
Remove the pulsation damper. You will need a 24MM wrench for this, because of how the threads are welded to the unit you can't fit the wrench in every position. Maybe you can take this off with a oil filter remover?
This is a good time to change your filter for the suspension.
The top is held on by a hook, remove by pressing down on the spring.
My fluid was black so I pumped out what was in the res. try to be as clean as you can be.
Fill up res to the engine off min/max, install filter.
I started the car and set it to normal height, check fluid level at engine on min/max. Raise up then normal 15 times if any major components were replaced while checking fluid level only when set in the normal ride height level. If you hear a hissing noise in the area where you installed the pulsation damper or in the rear of your car then shut it off and bleed at the same bleed screws.
I had the hissing noise so I had to bleed the system 5 times. I had no luck getting rid of the noise. I ran the rodeo and dynamic test along with testing the pump and other components and had no codes after I was finished.