help with battery temp sensors

I removed the temp sensors to recondition the battery modules. I cannot remember where one of the 4 sensors goes. It is the one closest to the connector. I think it is for air temp. The sensor does not fit anywhere that it will reach. There is a large hole in the sheet metal under where the connector goes, but the the sensor is too small to fit properly. It just flops around. see pic. What am I missing? In the picture, the sensor is on the bottom and the large hole can be seen. You might have to scrool the image.

 

I decided to drop the sensor into the hole in the sheet metal. Gravity might keep it there. I could find no way to lock it into place.