Description Reviews MINI Cooper S Pressure Converter Valve. We see these fail from time to time. This valve sends a vacuum signal to the turbo so that it knows when to be on and off of boost. Telltale signs that yours is bad is an elephant like sound right after you turn the car off, as well as low boost, or no boost, and a SES light. This part fits all MINI Cooper S cars with N14, N18, & all JCW cars. This is a new OEM MINI part in an aftermarket box.