Not that anyone asked...
Sensor failures and harness problems can give a false warning. My course would be to at least use the water drain feature to get a fuel sample into a clear container for visual inspection. To just assume that the warning is a bad sensor can have some serious negative consequences.
Fwiw, I tried all the other options first. Eventually trying the sensor. Which cured the warnings.
A failed sensor is apparently a common issue according to the dealer