Function Explanation (DTC Detection Outline)

• The PCM calculates the estimated engine coolant temperature based on the vehicle speed, engine coolant heat radiation amount and the operation conditions of the climate control unit. If the malfunction determination condition repeats 3 times, the engine coolant heat radiation amount is frequently high, and the estimated engine coolant temperature does not exceed 77 °C {171 °F}, the PCM determines that the thermostat has a malfunction and stores a DTC.

Fig 1: Vehicle Speed And Engine Coolant Heat Radiation Amount Graph

Courtesy of MAZDA MOTORS CORP.