I once remember an event did, sat on the start line, water temps all good, sat at 90deg, helmet on, you can't hear the engine too much only the co-driver, so, on the stage, doing really well, car starts losing power, hmm strange, looks at temp guage and for some reason, its gone back to zero, hmmmmm maybe the sender has broken, maybe the wiring has broken, thinking all this flat out (well was flat out till losing power) down shift, even less power, oil temp ok, water temp at zero.

eventually pulled over, and car had overheated (you can't tell engine temp in a rally car as it's fecking hot and fast as it is), only after a few mins of engine off did i realise that the water temp guage was not at zero, well it was, but it had gone all the way round back to zero off the top of the guage

Hence i alway use level sensors too