What Causes Low Engine Coolant Temperature

There are two main causes for low coolant temperature:

1. The thermostat is not sealing properly;
2. The coolant temperature sensor is faulty.

Two causes and solutions for low coolant temperature:

1. Thermostat not sealing properly:

The thermostat is a component that automatically acts as a valve based on engine coolant temperature, typically installed at the outlet of the radiator and inlet of the water pump. When coolant temperature is low, the thermostat blocks the flow of cold coolant from the radiator, preventing it from entering the engine water jacket, allowing the water jacket temperature to rise quickly - this is known as the small circulation loop.

When the coolant temperature reaches a certain level, the valve gradually opens, allowing coolant from the radiator to circulate again. This enables the coolant to flow through the radiator, slowly increasing the temperature while dissipating heat to the atmosphere, maintaining the engine at an appropriate operating temperature - this is the large circulation loop.

If the thermostat malfunctions and fails to close, keeping the coolant in constant large circulation, the engine temperature may remain too low.

Additionally, if the cooling fan runs continuously due to electrical faults, this can also cause low coolant temperature readings.

Solution: We recommend having the thermostat inspected at a 4S workshop.

1. Faulty coolant temperature sensor:

A defective coolant temperature sensor may display inaccurately low readings while the actual coolant temperature remains normal.

Solution: Prompt inspection and repair at a local 4S workshop is advised.