SIM settings icon always on notification bar
That is the SD card icon not the sim card icon.

Perhaps your phone does not recognise the SD card, or the card needs reformatting to be used with the phone.

Or you don't have an SD card inserted.

EDIT

After further research:

That icon is called "stat_notify_sim_toolkit." It is used in just two places, both methods inside com.android.server.MountService:

notifyMediaUnmounted()
notifyMeadiaChecking()

Tracing these methods backwards, I see that the MountService calls them when either:

1) a volume is detected as not mounted
2) it is checking to see if a volume is mounted

Num. 2 should only take a few seconds at longest.

So, "something" is not mounted properly, though I cannot guarantee that is the SIM that is having a problem.

You should remove and re-insert all plugable items (SIM, SD).



Another option recommends: 


  settings > applications > manage applications > SIM Toolkit > Select Force Stop button


If this removed the icon 'temporarily' at least it confirms it's a SIM problem and not SD.

EDIT 2

Someone has a recommended solution for NON-ROOTED phone's here:
(I cannot verify this method as I haven't tested it)

SimCard Notification Icon Fix

For rooted phones simply use Titanium Backup and FREEZE the app: Sim Toolkit