The temperature sensor is an e46 m3 CSL gear box temp sensor mounted in the refill plug (good enough for Getrag, good enough for us). The refill plug is customized to take the CSL sensor. A custom made measurement harness with BMW OEM parts is used, and the heat resistant silicon wrapped wires is surrounded by a heat protecting sleve.
Since the data for the CSL gear box temperature sensor is not available, the sensor had to go thorugh a calibration procedure in order to map its characteristics to temperature. Cumbersome, but now the characteristsics are known and implemented in the analog2CAN hardware to make high quality temperature measurements.