Code P015, Open ECT Sensor Signal: Notes
WARNING: This page is about a different car, the 1995 Cadillac Eldorado. However, it is still accessible from the selected car via links, so may be relevant.
Engine coolant temperature sensor is a 2-wire thermistor, whose resistance varies with temperature. Sensor signal is on circuit No. 410. Sensor ground is on circuit No. 476.
As sensor temperature increases, sensor resistance decreases. High coolant temperature will result in low signal voltage on circuit No. 410. Code P015 sets because PCM assumes coolant temperature cannot be -20°F (-29°C) or less when IAT is -9.4°F (-23°C) or greater.