I don't know if you know, but how does current idle compare to regular idle. Varying 4-8rpmm means smooth idle, but if the vacuum leak is constant it will still have a smooth idle.

I don't remember if the s40 has the vacuum diagram up in bottom passenger corner of your hood. It's there on the 850, which makes it easier to figure out whats line goes where.

The other guy mentioning that the Vacuum being reduced will raise fuel pressure makes a ton of sense.

That hose you reference does it then branch off to the EVAP canister? Firstly, Check the check valve.

Check the brake vacuum line, odds are it is plugged in, but if its not you find it!


Finally, have you driven it a bit yet? Hopefully another code will pop up and let you narrow it down further. Or, maybe you pushed a vacuum line 1/8" inch further and it sealed without you noticing and the problem is solved. Believe me, I've solved more problems without knowing what I did on these cars than they've made cars (or at least it seems...)