2003 A4 1.8t: Very high pitched noise coming from engine bay

[PhilR]

I figured I'd start in this section, here goes...

I just started a new job which results in a new commute (about an hour).

As of late, while driving my 2003 a4 1.8t has been making this ear piercing, high pitched noise that doesn't go away until I shut the car off. Its doesn't make the noise on startup, only after driving a while.

The noise stays at the same pitch and does not change with rpm. The pitch remains the same while at idle or @ 75mph on the highway.

I've checked under the hood several times in an attempt to identify where the noise is coming from but its so damn loud that I cannot even guess where its coming from. Also, the car continues to run and drive fine.

Any ideas???

[NFX123JMP]

Yes, it is your SAI pump failing-secondary air injection. It is emissions related. Your car will run fine without it functioning properly. Best bet is to get a used one or on the Web there is DIY on how to repair it.

[dudeman258]

Try removing your oil cap while the engine is running.

Walker

[audi_slavin]

i had the same exact thing happen in my a4 but it only did it for a night and it was fine the next day