Coolant is at the borderline to set the sensor

Coolant level is just below the sensor borderline. As the engine heats up, the coolant expands, turning off a low coolant warning light. When it cools the coolant contracts allowing it to drop below the required threshold and illuminates the light again.

Table of Contents

• 1. Causes
  • 1.1 Coolant System Leak
  • 1.2 Water Evaporation

Causes

Coolant System Leak

A leak in the cooling system will diminish the level of coolant. If it is a very small leak, it may take a while before a problem becomes evident.

Water Evaporation

Engine coolant is usually a combination of water and coolant. The water can evaporate, leading to a reduction of coolant. The coolant will have a higher gravity, or density, if some of the water has been evaporated.