Flashing Coolant Sensor

How do folks, bit of help if possible. Driving home yesterday and the coolant level light starts of on one.  Pulled over checked level and all good no problems there ( I did top up the coolant a little Sunday but not but much). Anyway I tried the usual Ive bridged the pins on the sensor plug itself and I have removed the replay (number 42) from the block and the light is still on and flashing.  On turning key to pos 1 you get the check, I start the engine and no light for about 30 secs and then it starts flashing. Any ideas of what else I can test. My assumption is by unpluging the replay the light should just stop altogether but it doesnt…any other tests I can do….Thanks in adavnce

ps happy xmas…

Have you had a look at the sensor itself? Unscrew it from the tank and clean it up. They can get hideously dirty ...

yeah tested all those things, even replaced the sensor last year so thought it highly unlikely it being that. However after reinvestigation of the relay again I unplugged it and left it unplugged again over night.  This time no flashing light after start up so I can only think the relay was at the time of me last checking it on its way out and intermittently failing, and now fully kaput…. im not sure.  The upshot is it was the relay so will replace over xmas…..