Where are you ordering from, and what part nbr are you using to order?
Are you using one of the online part database sites like
www.realoem.com or
www.bimmercat.com and typing in your VIN so that you get the correct diagrams for your car?
Item #2 in the diagram below is the cap for the Turbo/intercooler reservoir (up front):
The cap for the main coolant system (near the firewall) is #6 in the diagram below:
