| 摘要 |
A method for diagnosing engine thermostat is presented. Indicated engine coolant temperature is estimated based on engine operating conditions, such as engine speed, net engine torque, air flow, fuel-air ratio, net engine torque, etc. This estimate is compared to the reading of the engine coolant temperature sensor in areas below the temperature at which the thermostat starts to open and above in order to detect degradation in the performance of the sensor or the engine thermostat. If the estimate and the reading agree in one area and disagree in the other, then the thermostat performance is degraded. If the estimate and the reading disagree in both temperature ranges, then the coolant sensor performance may be degraded.
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