Good evening.

I have a 2006 Volvo S40 2.4i.

I have a check engine light on (which indicates running rich) and a high pitch whistling noise which sounds as if it is coming from the rear of the vehicle.

I have replaced the fuel pump, fuel rail pressure sensor and oil trap. The engine light is still on and whistling noise remains. I have removed the oil cap while the vehicle is running but the whistling remains.

Any thought as to what this might be or what steps to take to analyze and get this corrected?

Thanks.

 

can you hear the whistle at idle or when the revving while parked and does it vary by road speed or engine speed? The running rich could indicate a vacuum leak or an exhaust leak (particularly with turbos). Which code did you get? Start by visually inspecting vacuum lines and try listening from different spots around the car & under the hood.

 

Is it the evap pump?

 

I also have a s40 t5 AWD 2.5...and I am getting a high pitched whistle too, mine in particular IS happening on ALL revs that reach 2500 or more, and gets worse with the load I apply...
I still have a great amount of power, but I don't think the whistling sound is healthy...
I am currently not showing a check engine light and the car does kinda spudder???? in all gears if the rpm's don't get above 1400 and I barely touch the gas(like when I CRUISE home after a tired day at work)
but if I punch it I have a lot of power and then that whistle....idk any thoughts?

 

I'd be looking and listening for an air leak somewhere, possibly in the intake air path. I'd also listen around the turbo itself going back through the exhaust for a possible leak as well. I saw something similar on a big block Corvette - which turned out to be air leaking between the carb (a 780 Holley with ports big enough to stick your arm in LOL) and the intake manifold.

 

For you I'd bet the PCV/Oil Trap clog issue. It has an extended warranty.

 

hey thanks for the reply, i checked the air pathing and it seems the noise is coming from the k&n intake contact to the manifold, but i cant be sure, its such a small area back there(the passenger side firewall area, but under the hood) its hard to recreate the noise wen the car has no way for me to push the accelerator from under the hood...so i have to get help from a buddy... I took it to kind of a cheap mechanic i suppose you can say and he checked it out for me free of charge and told me it was nothing to be worried about that my aftermarket K&N intake system was whistling at the bend and that is normal for my car...any thoughts on that?