Unsuitable is the ambiguous word.
There could be more to it than that, by range is the conditions of the system out of range of the sensors physical capabilities?
Is the sensor in it the wrong sensor?
Is the company using the equipment for a purpose the machine isn't actually designed to do?
It doesn't state whether this is a previously running machine that has degraded, or a new piece that isn't doing what some one thought it would when he bought it.
Who made the determination that it is the sensor, a tech, supervisor, operator?
All of these things makes a big difference on how much you take at face value "sensor is unsuitable."
That is why I would go ask someone more familiar with the issue, changing and tweaking ranges may very well be the answer or it could be more.
Yes I did answer my questions in college that way, I am not making a decision to change something unless I know more information than (basically this all that's given) sensor doesn't do what I want it to .