Driving my 94 E320 last night after dark on the interstate. Traffic moving about 60mph, outside temp about 85F, coolant temp gauge at about 90C, everything seems fine except the coolant temp idiot light is faintly glowing. Drive home turn engine off, check coolant level everything is OK. No leaks last night, none this morning. Drive to work in bright sun, can't see the light, pull into the parking garage and see the light dimly illuninated. Any ideas?
regards,
Mark

Mine stays lit too, i'm thinking the sensor gets crud on it and stops working?

it is not the coolant temp idiot light, but rather the coolant level idiot light, as stated in the previous post it does build up crud and will illuminate faintly.

The sensor located near the bottom of the coolant tank gets corrosion buildup on the terminals and prematurely sets off the idiot light. You can clean the probes as a temporary measure, but it will work for about a week or so before it starts acting up again.

Buy a new sensor (around $40 I think) and be done with it...15 minute job.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Thanks to all who responded to my question.
regrds,
Mark

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