The coolant level sensor is the electronic sensor that is responsible for measuring the coolant level of your engine. It is usually installed in the coolant reservoir or radiator, and measures the amount of coolant in the system to make sure that it is always at the proper level. When the level drops below a safe level the low coolant light will come on to alert the driver that coolant must be added. Low coolant is dangerous to the engine as the coolant is what keeps the engine from overheating during normal operation, so it is imperative to replace the coolant level sensor if it is failing.
1. Coolant Light stays on
One of the most common symptoms of a faulty coolant level sensor is a Coolant Level Light that stays on. If the sensor shorts, it can cause the Coolant Level Light to stay on. This is a problem because a permanently illuminated coolant light will not be able to properly alert the driver if the coolant level does drop low.
2. Low coolant
Another symptom of a problem with the coolant level sensor is low coolant. If the coolant level drops low and the light does not come on then that means the sensor or wiring are having a problem. The sensor is designed specifically to detect low coolant, so if the level in the reservoir drops low, and the light does not come on, that may be an indication of a problem with the sensor or perhaps the wiring.
3. Engine overheating
The engine overheating is another indicator of a problem with the sensor. Engine overheating can be caused by a variety of issues, usually not related to any sensors. However, if the overheating is related to coolant level, this may be an indicator of a problem with the sensor. If the coolant level drops low enough to cause overheating, and the low coolant light is not illuminated beforehand, then that may be an indicator of a problem with the sensor.
While the coolant level sensor doesn’t play a big role in engine performance or drivability, it does serve a very specific purpose in protecting the engine from dropping low in coolant and potentially overheating. For this reason, if you suspect that your coolant level sensor may be having an issue, have the vehicle diagnosed by a professional technician, such as one from YourMechanic. They will be able to inspect your vehicle and determine if your car will need a replacement coolant level sensor.
This article originally appeared on YourMechanic.com as Symptoms of a Bad or Failing Coolant Level Sensor and was authored by Ed Ruelas.