Primary Coolant Temp Dynamic Monitoring

To ensure the primary ECT sensor has not stuck below normal operating range, a simple dynamic check to verify a minimum rise in coolant temperature over a calibratable time has been implemented. If coolant temperature at start is greater than -35 deg C and less than 54 deg C, the monitor is enabled. At -35 deg C, the coolant is expected to rise up to -7 deg C in 291 seconds or less. If -7 deg C coolant temp. is not achieved in the required 291 second timeframe, a fault is detected. At a -7 deg C start temp, the coolant is expected to rise to 40 deg C in 5450 seconds- assuming worst case with EGR off, vehicle idling in neutral with heater on. Again, if the minimum temperature is not achieved in the required time, a fault is detected. This diagnostic is used in conjunction with the oil vs. coolant plausibility check, thermostat model, and SRC checks to verify proper ECT operation and engine warm-up.