electronic noise from engine bay

[carlton1967]

Hi can anyone help me with this,i have an electronic sounding noise coming from under the engine bay of my 2003 A4 2.0 fsi avant doesnt do it every time i start engine but from time to time does it it doesnt seam like its a belt or something like that but as if its something electronic

[bez101]

can you explain the noise

[carlton1967]

its like a high pitched electronic squeal but doesnt do it all the time,if i turn off ignition and start car again sometimes it stops