Check emission after removing acoustic valve

I've got the check emission light after I've removed the acoustic valve. Anyone encounter this before? Should I put it back on? Or leave it?
 
You can remove it but you need to keep the bit that plugs into the wire and you also need to plug the vacuum hose up.
 
opens up the second inlet at 4k rpm, suppose to be noise reduction at 4k and below. but like been said, block up the vacuum hose from the plenum, and keep the solenoid connected to the electrical plug. tbf when i did mine i just disconnected the vacuum hose off the solenoid blocked the hose off, kept the acoustic valve fitted and ran a cold air feed from the lower grill.
 
It's kind of scary now, I've done 3 x10 mins journey but the light is still on.
And I notice then when I connect the whole thing back the butterfly valve won't close.
 
It's kind of scary now, I've done 3 x10 mins journey but the light is still on.
And I notice then when I connect the whole thing back the butterfly valve won't close.

the default position is open - vacuum is applied to close it - so if it goes faulty it stays open
 
On tick over it will be open, then will close as you pull off, and open again once you go past 4k rpm.