Coolant Sensor: Advantages and Disadvantages

This page explores the advantages and disadvantages of coolant sensors, also known as coolant temperature sensors.

What is a Coolant Sensor?

Introduction:

• A coolant sensor functions as a temperature sensor, much like a thermistor.
• It’s an NTC (Negative Temperature Coefficient) type sensor.
• When the coolant temperature increases, its resistance decreases. Conversely, when the coolant temperature decreases, its resistance increases.
• It’s typically located on the cylinder head of the engine.
• It’s used to control the cooling fan of the engine, turning it on or off, and to activate emission controls.

Image Alt: Coolant Sensor Connection Diagram

Benefits or Advantages of Coolant Sensors

Here are the benefits and advantages of using coolant sensors:

• Engine Overheat Protection: They protect engines in cars and other vehicles from overheating.
• Simple Measurement: They only require a two-wire measurement of resistance in ohms.
• Fast Response: They provide a quick response to temperature changes.
• High Sensitivity: They are very sensitive and offer a significant output change based on the input temperature.
• Accuracy: They are more accurate compared to RTDs (Resistance Temperature Detectors) and thermocouples.
• Cost-Effective and Compact: They are inexpensive and available in small sizes.

Drawbacks or Disadvantages of Coolant Sensors

Here are the drawbacks and disadvantages of using coolant sensors:

• Limited Temperature Range: They have a restricted temperature range in which they can operate effectively.
• Current Source Required: They require a current source for operation.
• Fragility: They are fragile and can be easily damaged.
• Non-Linear Output: The output is a non-linear function, which can complicate data interpretation.
• Self-Heating: They are prone to self-heating, which can affect accuracy. To minimize self-heating error, it’s essential to limit the sensing current to a lower value.