I have a 2000 honda civic si and there’s a constant ringing noise, i thought it was a vacuum leak but i got that fixed and it’s still making the noise. Anyone have this issue or know what it could be ?

 

Post a video from multiple angles of the engine bay. Otherwise we can't help.

 

Ok it was pretty faint but at other times you can hear it much better but it’s definitely coming from this side of the engine bay.

edit: I tried attaching the video but i don’t think it’s working, it’s coming from the drivers side of the engine bay if that helps.

 

Try to put something up on YouTube and attach that here. If you can't can you better try to describe the ringing noise?

Does the noise change with RPMs? Does it go away at a certain RPM or get louder when you change something?

From the diver's side it could any number of things:
Alternator bearing
A/C compressor (If applicable)
P/S Pump (If applicable)
Timing belt tensioner

If you have a small hose, you can try to put one side in your ear and move the other end around the engine bay to see if you can further isolate it. You can also do the same with a long screw driver: handle side on your ear and touch the metal tip to various pieces of the engine. Obviously be careful of moving parts.

One other thing is to get the motor running and slowly, and carefully unscrew the oil cap. Don't fully remove it, but lift it just a little bit and listen if the noise gets louder indicating it might be coming from the valve train.