This warning light turned on 3-days ago on my LS 400 (1990). I checked under the hood and saw that fluid was indeed leaking from the base of the sensor attachment on the overflow tank. Off to the dealer and one new overflow tank, new sensor, new tank cap etc. (and $423.00!) was installed.
Now the radiator warning light turns on about two-or-so minutes after engine ignition. Have used the car for one day with this new condition as the temperature guage is steady and apparently the car is not overheating. The coolant levels seem okay too.
A mechanic friend said I shouldn't worry about it.
Any views from this knowledgeable group?