Just last night driving to work in my 05 wrx and the engine management light came on. At this point nothing seemed wrong everything was running fine I stopped at some lights give it a little rev and noticed a slight howling sort of noise that goes up and down with the revs. setting off the noise is there up till about 2500rpm then you can't hear it can anybody help.

 

Some sort of bearing noise?

I'd get it diagnosed PROPERLY soonest.

 

Thanks for your response no it sounds air related when the car is still it goes up and down with the revs when you rev it

 

Check intake pipes for one split or dropped off then.
There a re a few smaller ones attached to the intake manifold that need vacuum too, check them at the same time.