What is a coolant level sensor?

The coolant level sensor, as its name suggests, keeps track of the coolant level in the engine. When working properly, the coolant level sensor informs the driver when their coolant level is too low, which can prevent overheating and engine damage.
The coolant sensor will set off some form of “Check Coolant” warning or symbol when your coolant level is too low.
The sensor usually either floats in the coolant reservoir or is positioned under the coolant reservoir’s cap.

When do I need to replace my coolant level sensor?

Knowing when to replace the coolant level sensor can be tricky since a broken coolant sensor won’t be able to tell you something is wrong.
The two indicators the coolant level sensor isn’t working are:
  • The warning light is on even if the reservoir is full of coolant
  • The warning light is not going off even when coolant levels are too low
You’ll want to get your coolant level sensor repaired as soon as possible. Low coolant can cause engine overheating and other problems. This can lead to much costlier repairs down the road.

How to replace a coolant level sensor

Here’s how a mechanic will replace your malfunctioning coolant level sensor:
  • The coolant reservoir is opened
  • The coolant reservoir will be drained to below the level of the sensor
  • The electrical connection is removed and the coolant level sensor is removed
  • A new sensor is installed and the coolant is replaced
Once the new sensor is installed, the car will be run to test that everything is working properly.

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