Logic of naming sensors in VW-group is simple it contains "G" (german "Geber") + sensor number. The sensor number is unique. Here you can find fitting location, connectors and pins description, some information about sensors signals.
To our mind, sensors information is reference, so there is only simple search by sensor number.
By way of the temperature sensor -G18 the coolant
temperature in the heater unit is monitored and heating regulated. The
additional water heater also features a second NTC temperature sensor
(additional/auxiliary heater temperature sensor 2 -G587) in the heater unit.
This improves monitoring and control of the water temperature.