Onan 7.5 Diesel Generator shut down problem

Genset could and has quite a few times, just shut down without warning. Will start right up and run for only five minutes or so and continues with the same routine over and over again. Throws a code 24 saying that it's not sensing coolant temp. in first 5 minutes of operation. Then the next day, it runs fine all day long and maybe for days after, so you never know when the next time will be. I'm about to change the sensor, but am hearing about a very expensive module that could be bad as well.
Now, other than a loose wire on the sensor, I can't think how something like this, could have an intermittent problem of this nature.
Anyone experience this and what might have been the culprit?