Pcm Code E037, Shorted Mat Sensor Circuit: Description
WARNING: This page is about a different car, the 1992 Cadillac Seville and 1992 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
MAT sensor is a thermistor that varies its resistance with temperature. As sensor temperature increases, resistance decreases. High temperature will result in low signal voltage. PCM Code E037 sets when PCM sees a MAT sensor reading of 298°F (148°C) when coolant temperature is less than 212°F (100°C).