Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. Symptoms of a Bad or Failing Low Water Sensor

Symptoms of a Bad or Failing Low Water Sensor

water sensor

Low water sensors are more commonly known, or referred to, as coolant level sensors. The purpose of these sensors is to alert the driver of low coolant level in the engine cooling system. When coolant level in the engine is low, the cooling system cannot adequately remove excess heat from the engine. This causes the engine to overheat which will lead to eventual engine failure. The most common results of engine overheating include warped or cracked cylinder heads, and blown head gaskets.

Normal operation

The typical coolant level sensor has two probes that, when inserted into engine coolant, pass electricity between them. This creates a complete electrical circuit. When coolant level falls below the probes, the circuit is broken and the low coolant level warning lamp is illuminated. This alerts the driver to have the cooling system checked.

There are basically two symptoms of a failed coolant level sensor.

Low Coolant Warning Light always on

Since the Low Coolant Warning Light is illuminated when the lamp circuit is electrically open, the sensor could go open internally regardless of actual coolant level. This would cause the coolant light to always be on. The necessary repair here would be to replace the sensor.

Low Coolant Warning Light does not illuminate on low level

If the coolant level sensor is electrically shorted internally, the coolant level circuit will never go open when coolant level falls too low. This prevents the Coolant Level Warning Light from illuminating and alerting the driver to a potentially hazardous situation. If the cooling system isn’t checked on a regular basis, engine damage may occur.

Have a trained technician like those at YourMechanic diagnose the condition. If the sensor needs replacement, they can do that. If another issue is the cause, they can fix that, too.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Still not sure about your car's issue?
Diagnose your car
What kind of issue are you experiencing?
Brakes are squeaking
Car is not starting
Car is overheating
Car is shaking (vibrating)
Fluids are leaking
Heating and A/C
Smoke or steam is coming out of the car
Warning light is on
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Find the Keyless Code on a Ford Explorer or Mercury Mountaineer
Many Ford Explorers and Mercury Mountaineers were manufactured with an option known as the Ford keyless entry keypad. Some models refer to it as SecuriCode as well. It...
Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...

Related questions

Q: I got a alternator replaced on my car and now the Check Engine Light is on with the Battery Light. My headlights are still blinking.

Hi and thanks for contacting YourMechanic. This sounds like there is a loose ground or a wire was not hooked up to the alternator correctly. Check all of the wiring when that was removed when the alternator and battery was...

Q: Can a faulty sensor keep the engine from starting?

Today's automobiles use many different sensors to signal engine controls and computer circuits to start a vehicle's engine and run all the programing for fuel, timing, and emissions control. Bearing this in mind, it is critical for the vehicle's main...

Q: Car won't start after overheating - 2013 Chevrolet Cruze

Hi there. The main issue that occurs when an engine overheats is that excessive coolant sprays on critical electrical components and reduces the vehicle's ability to start after it overheats. However, in some instances, if the engine was damaged due...