Or, you can just replace all of your caps. I see them sold on ebay as a set quite often. Check this out...

http://search.ebay.com/mercedes-gas-cap_W0QQsofocusZbsQQsbrftogZ1QQfromZR10QQsatitleZmercedesQ20gasQ20cap*

__________________
Willy

'94 E420 White

Mods
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Berg Werks Keyless Entry
Buzzer replaced with Chime
Dash Light Upgrade
Burlwood/Leather shift knob
Alpine CDA-9815 Head Unit
2002/2003 16" C Class 7-Spoke Wheels
Updated "Chip" to fix Code 19 problem