What causes the slow rise in water temperature?

[JesseAnn]

Water temperature rises slowly due to a damaged thermostat causing the coolant to continuously circulate in the large loop. The speed at which the water temperature rises is determined by the water temperature sensor's perception of the water temperature level. The functions of the water temperature sensor are: 1. Convert the coolant temperature into an electrical signal and input it into the ECU system; 2. Adjust the fuel injection quantity; 3. Adjust the ignition timing advance angle, increasing the ignition advance angle at low temperatures and preventing detonation and ignition delay at high temperatures; 4. Influence the idle control valve, where the ECU controls the idle control valve's operation and increases the idle speed based on the water temperature sensor signal at low temperatures; 5. Affect the EGR valve.