The coolant temperature sensor is the device that sends data to gauge the temperature of the coolant in an automobile engine. The engine computer uses this data to regulate the fuel mixture for maximum efficiency and minimum emissions.
Role of Coolant Temp Sensor in Controlling the Fan
The coolant temperature sensor is the control point that regulates the air coming into the radiator. As the coolant temperature rises, more air will enter, pushing more coolant through the engine. As temperatures fall, less air enters, and intake system pressure is down slightly. Airflow is controlled to match engine needs.
As voltage from the coolant temperature sensor increases, the electronic device sends a signal to the radiator cooling fan relay to turn on the blower motor. As voltage from the sensor decreases, voltage to the relay decreases and current through the relay contact is reduced, and the fan turns off after a short time.
The temperature of the coolant is influenced by several factors, including engine load, airflow through the radiator, ambient temperature, etc. The coolant temperature sensor responds quickly to these changes, so airflow follows temperature changes accurately within no time.
The coolant temperature sensor is designed as a solid-state electronic device and emits a small current to the circuit. The sensing element of the coolant temperature sensor is a thermistor. Thermistors are designed with a positive temperature coefficient, so as their temperature increases, resistance decreases, and voltage increases. All automobile manufacturers now provide coolant temp sensors with varying ranges 150°F-260°F (-100°C-125°C)or -25°C to +125°C), so they can be used in different parts of the world.
The purpose of the coolant temp sensor is to keep the engine’s valve timing and cylinder head temperatures at optimum values for maximum efficiency and minimum emissions. The engine computer monitors the coolant temperature and accordingly controls the fuel mixture to meet peak efficiency and performance. It is done without running too lean or too rich, which can cause excessive exhaust emissions.
Coolant Temp Sensor Working in Cooling System
The cooling system in an automobile engine heats up or gets hot when it runs with a high load or aggressive acceleration. As it gets hotter, more air will enter the radiator, lost inside the fins. At the same time, heat from the engine will be dissipated as air flows across the radiator core. The coolant temperature sensor is designed to control the cooling fan according to coolant temp data.
The cooling fan is powered by a relay that switches on and off according to coolant temp signals from the coolant temp sensor. If the system starts overheating, the cooling fan turns on even at low engine loads or road speeds to keep engine parts from overheating. As a result, better cooling performance can be achieved without overheating engine oil and other engine parts.
Cooling fans are made with electric motors attached with blades for cooling by blowing air across a surface. It is called a centrifugal fan. The fan’s speed is governed by a computer, which determines whether or not the fans are to run according to coolant temp signals. Cooling fans are being used in automobiles for more than 30 years with no problems.
Reasons of Coolant Temperature Sensor Failure
All automobile manufacturers provide coolant temp sensors so they can be used in different parts of the world. They are designed with mechanical linkages that can be damaged due to road debris or water that flows into them while washing an automobile. It will result in a loose connection between sensor pins and electronic circuits. It will lead to inaccurate signaling of coolant temp data, which adversely affects cooling system performance.
Coolant temp sensors can also fail electrically due to improper resistance of the sensing element. It is especially true if the car has been sitting for a long time or has just been driven through water, which will cause moisture into the sensor. Coolant temp sensor failure can also occur due to overheating due to excessive airflow or under-cooling due to clogged radiator, bad fan, or blocked airflow by mud or snow.
Coolant temperature sensors are pretty reliable but must be tested periodically to ensure the maximum performance of your vehicle’s cooling system. It is not uncommon to find that the temperature sensor in one vehicle will fail at one time and be fine in another car. Inspect your vehicle immediately if you notice any symptoms of sensor failure.
Top Coolant Temperature Sensors:
- Dorman LiquiCool:
This is the only sensor on the list compatible with all vehicles, from Honda to Mercedes. The sensor can be mounted in a single or double thread hole and is perfect for any engine compartment.
- Denso OE Exact Fit:
Designed to make a clean installation, these sensors are custom-designed for your vehicle and easy to install by anyone. They come with a four-year warranty and last for years of reliable service.
- Prestone Heavy Duty Coolant Temperature Sensor:
These sensors come in either steel or brass construction, which makes them resistant against corrosion from coolant leaks. They are designed to be installed in the vehicle’s radiator.
- Gates Thermostat:
This sensor is an excellent choice for those who have a newer vehicle that does not have the Clymer T-1 or T-2 sensor. It installs into a single-threaded hole and can be used on virtually any coolant type.
- Bosch Coolant Temperature Sensor:
The Bosch coolant temp sensor is designed to be installed in all types of vehicles and is specifically made for the most popular coolants.
- Delphi Coolant Temperature Sensor:
These sensors are made to replace the factory-used T-1 or T-2 sensor, making them the most cost-effective solution.
- Dumonde Kool-Stop:
This thermostat can be used on vehicles with a bracket and costs less than $10. It’s designed to fit any vehicle and can last up to 100,000 miles (161,542 kilometers).
- WeatherTech Radiator Thermostat:
WeatherTech radiator thermostats are specially designed to provide temperature control and reliability. They’re perfect for heat-sensitive materials like soft-drink bottles, soup cans, computers, or any other device that will get damaged by extreme heat.
A coolant temperature sensor plays a vital part in the operation of your vehicle’s cooling system. It should be located in an excellent area to deliver accurate signals to the computer, determining if the cooling fans should be switched on or off. If it delivers false signals, you should test and replace your coolant temp sensor because engine parts will overheat and could be damaged. Suppose you experience trouble while driving, such as rough idle, engine misfire, or hesitation. In that case, it could also indicate that the coolant temp sensor is not working correctly and needs to be tested or replaced.