Does anyone have a photo or diagram of where it is?

Thanks

From my experience with other models, l am guessing it is mounted IN the radiator, just below the upper radiator hose. It will have two wires coming out of it, & a plastic connector that unclips first, the unplugs with a tugging.
This is true of the 205, 306, 106 models.

CAREFUL ! there r probably two coolant sensors. One senses the temperature of coolant inside the radiator. The other senses water inside the motor block. Just in case ur water is NOT circulating, one of the sensors will KNOW IT.
The other sensor is very close to the thermostat mounting & is usually located where the upper radiator hose enters the motor block. l do have a photo of that, from a 306, sorry:
http://i255.photobucket. com/albums/hh155/trevor_trillion/ 306thermostat003.jpg
http://i255.photobucket.com/albums/hh155/trevor_trillion/306thermostat003.jpg

click on the second blue one.
see the green plastic connector on the temp sensor?

the coolant temperature sender is located on the right hand side of the cylinder head as u look at the engine from the front of the vehicle & controls the temperature gauge on ur instrument panel.Not to be confused with the cooling fan sender unit which is located in the side of the radiator & can have either two or thee wires coming out depending on the model.If ur fault is the temperature gauge not working change the sensor located on the cylinder head.If u r overheating because the fans r not cutting in to cool the engine then change the sender unit located in the side of the radiator.