Take the plug out ....it will stop. I got tied of weekly cleaning myself. If you need good sensor ...follow the link:
http://catalog.eautopartscatalog.com/taylor/wizard.jsp?partner=taylor&clientid=taylorautomotive&baseurl=http://www.taylorautomotive.com/&cookieid=1KZ1D6N5H1L41BBH0I&year=1994&make=MB&model=E-420-001&category=G&part=Coolant+Level+Sensor,
I got tied of changing a milion small little components that all sums up to huge numbers.
Had an old Accord long time ago with over 200k on it and no crazy lights on the dashboard whatsoever.... no fan cklatches...no head gasket leak... no headligt wiper motor acting funny...no five link suspension that needs replacement twice a year ....no sping perches... no wheel alignment and tire ballancing with evry tire rotation....no....no no... But I am driving a benz....I guess if I would of put half of the love($) that I put in this benz on that old Accord probably now it would of have 2 milions miles and still running....

__________________
New Addition to the family
2013 Passat TDI 5Miles
2004 E500 4MATIC Wagon 95k
1996 E300 Diesel 173k Sold
1993 300E 2.8 230k Sold
1994 E320 White Wagon 373K Sold
Still dreaming about ....500E


Radu Negru