Coolant temperature sensor – ECT sensor

The coolant temperature sensor or ECT (for its acronym in English, Engine Coolant Temperature) is a component found in the vehicle’s engine. Next, you will learn what it is exactly, how it works, and its usefulness. As well as where it is located and what are the faults that it commonly presents.

What is the coolant temperature sensor?

ECT sensor is in charge of measuring the temperature and monitoring the cold start, and this is because the injection systems have begun to maneuver. Therefore, a sensor is required to warn and send information to the ECU and thus vary the amount of fuel as necessary.

The ECT sensor is a significant engine device. This uses a resistor, which induces the voltage drop towards the machine, thus configuring the air/fuel composition, and the injector’s pulse stabilizes. In this way, the temperature can be calculated.

Also, the coolant temperature sensor is responsible for sending information to the computer. To do so, activate the motorcycle ventilation.

What is it for? Coolant temperature sensor function

The ECT’s main function is to calculate the temperature of the engine coolant. Then, it sends this information to the computer, and it controls and normalizes the injection system. As well as modify the composition of the air/fuel.

How does the ECT Sensor work?

Because this is a thermistor, the hotter it gets the less resistance. Therefore, it sends a signal to the ECU, which is not linear; on the contrary, it is proportional. The ECU can receive the information, decipher the values and transform them into a coolant temperature index.

On the other hand, if the engine is cold, the machine increases the fuel injection time and the persistence of ignition. However, the engine temperature is considered so that it does not drop so low that it shuts down. In this case, the Check Engine lamp will light.

Coolant temperature sensor location

To find the location of the ECT sensor, you must go deep or low in the engine. There, you’ll find it screwed into either the internal intake compound or the cylinder head. So, this will always be close to the zone of the passage of the refrigerant to have continuous contact with the fluid.

ECT Sensor Types

The only ECT sensor type that exists is the NTC thermistor, meaning a negative temperature factor resistor.

So when the temperature is very high, the conductivity of the sensor is higher. However, this relationship is not linear but adjustable. That is, it does not perform Ohm’s law.

OBD2 codes related to the coolant temperature sensor

The ECT sensor is responsible for sending information to the computer and the injector system. In this way, the motor operates normally. However, when failures occur, they must be differentiated from each other to attack the problem. So, OBD2 codes have been established, among which are:

  • The DTC P0117 code is set when the PCM senses that the signal voltage is below the normal range, which prevents the sensor from working.
  • Likewise, according to OBD2 (or on-board diagnostic system) the faults P0118 and P0125 are also found .
  • On the other hand, the P0070 is the ECT circuit.
  • P0071 means category / occupation of the coolant temperature sensor
  • Also, the ECT Sensor circuit, low input is P0072 .
  • Whereas, the same high-input code is
  • Lastly, the intermittent coolant temperature sensor circuit uses the code

Common ECT Sensor Faults

The coolant temperature sensor is a fundamental part of the engine because if it does not fulfill its function well, it will also affect the injection system. So, it would be best if you recognized what some of the most common failures are. Among them, we can mention:

  • Attempting to start the car cold presents problems.
  • Idle or wavering idle.
  • Even if the engine temperature is optimal, there are difficulties when starting.
  • Massive fuel expense.
  • Disadvantages when activating the electric cooling fans.

How to test if the coolant temperature sensor works?

You need to know how to test the ECT sensor to diagnose any faults. In this case, you should check if the ECU is outside the minimum and maximum temperature measurements. If so, there is a fault in the NTC resistance of that sensor. So this one has an opening in the circuit.

In addition, it will present all the above-mentioned failures. Therefore, to verify that it is in perfect function, it must show the following values:

  • Between point C and A, the resistance must be 2.5 kΩ when the coolant temperature is at 20º Celsius. This is used as a signal to intervene in the injection method.
  • On the other hand, when the coolant temperature is 80º Celsius, the resistance should be around 0.05 kΩ, between point C and A. In this case, it serves as an indication of instrumentation in the tool compartment.

How to clean the ECT Sensor?

If you want to clean the ECT Sensor, you don’t need to be an automotive engineer, and you just need to know where it is located. Once viewed, it is unscrewed for maintenance from the outside. Now, since you have it in your hands, you should wash it well.

For this, use a spray with which you will spray it well. Likewise, the process ends by drying it with pressurized air. This is important, as old fluid accumulated in the coolant can cause the sensor to fail.

Now, you already know what the coolant temperature sensor (ECT) is for; you are better prepared if an engine failure occurs. Therefore, remember to do good maintenance always to have good electrical operation.

Coolant temperature sensor – ECT sensor

Hi, this is Viney Bhatia, a blogger, an engineer, and your virtual mechanic. You'll get all the latest information about cars, reviews, tips, service methods, and various other things related to automobiles on our blog.

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