Weird sound 2012 S60 T5 with mass air flow engine light.

[xxblindxx]

I recently popped a few codes on my '2012 Volvo S60 T5' and there is a strange hissing sound coming from the car. I recorded the sound and uploaded it to youtube (link below).

The sound only start after the car is warm (about 30+ min of driving) and is only present at idle or very low RPM. Once i accelerate, the sound goes away. When the issue is happening, the car has a very slight misfire. I'm guessing these two issues are connected because there is no misfire if the sound is not happening.



P0101 - mass or volume air flow A circuit range/performance
P0300 - random/multiple cylinder musfire dected
P0301 - Cylinder 1 misfire detected
P0302 - Cylinder 2 misfire detected

I plan to replace my plugs and coils seeing as it is getting close to that time, although i'm not sure if the hissing sound is related to the mass air flow sensor or it could be a different issue.

Any help would be appreciated!

[KnucklesBusted]

Hello,

I could not get your video to play but there is a common issue for that car when the PCV system fails, the PCV valve does not close at idle. The valve should be near closed at idle (high manifold vacuum) and modulates to open at higher RPM. When it does not close at idle this very high crankcase vacuum causes a "whistle" sound as air is being drawn into any gaps it can find.

To trouble shoot remove the oil fill cap or dipstick when it is whistling. If the sound and the engine RPM change that is the PCV issue.

Unlike other systems you may have run across that engine uses a fairly complex unit. It is located beneath the intake manifold and is incorporated into the oil filter housing. The OEM part is available online for ~$210. It cannot be serviced, it must be replaced as a unit, it is glued and snapped together and will be all gummed up inside anyway, it is also heated electrically.

Not too bad to change out, you just have to remove the air boxes, the manifold can stay on.

That might be your issue, not sure but maybe worth checking.

My opinion is that your codes could be coming from this, the stuck valve is essentially a air leak into the intake system resulting in a too lean mixture the ECM must try to balance out.

[xxblindxx]

This seems to be the issue! When i take the oil cap off, the sound stops and you can feel a large amount of air being sucked in where i took the cap off. Is the actual part that needs to be replaced the "oil filter housing" or could it be a different part of the PCV system that is clogged up?

Thank you for the help!

[xxblindxx]

I'm going to purchase the oil filter housing. Would it be a good idea to replace the 'PCV hose' as well? (links below).

https://www.fcpeuro.com/products/volvo- ... g-31338685
https://www.fcpeuro.com/products/volvo- ... vo-8670008

[xxblindxx]

For anyone reading this having the same issue, it was solved by replacing the oil filter housing.

Here is a good youtube video on the steps to replace the part.