DTOZH - what is it? DTOZ verification

In modern cars, the engine is controlled by an electronic unit that receives information about the health status of its systems using appropriate sensors. The cooling system, designed to ensure optimal temperature conditions of the motor, includes several such signaling devices. One of them is the coolant temperature sensor (DTOZh). What is this device and what are its functions, we will describe in this article. In addition, we will consider possible malfunctions of this element of the cooling system, as well as methods for their diagnosis and elimination.

DTOZH: what kind of sensor is it and why is it needed?

The coolant temperature sensor is designed to obtain information about the temperature of antifreeze or antifreeze in the system and its subsequent transmission to the electronic control unit. Based on this data, the car controller controls:

• idle speed when the engine warms up;
• fuel concentration in a combustible mixture;
• turning on and off the cooling radiator fan.

The principle of operation of the sensor is quite simple. It is based on the properties of semiconductors to change their electrical resistance under the influence of temperature.

What is a temperature sensor? DTOZH consists of the following elements:

• body (cylinder);
• semiconductor thermistor (a resistor that changes resistance when the temperature changes);
• conductive spring;
• electrical connector.
  

How does DTOZH work?

The coolant temperature sensor has two electrical contacts, one of which is a body that closes to ground, and the second is a “+” that goes to the electronic unit. The controller sends a voltage of 5 V to the DTOZH, which is transmitted to the working element using a conductive spring. The semiconductor thermistor itself has a negative temperature coefficient, and when the coolant in which it is placed is heated, its resistance begins to decrease. At the same time, the voltage decreases. It is by changing it that the electronic control unit calculates the temperature of the coolant in the system.

The temperature sensor, due to its simple design, fails quite rarely, but if this happens, it is replaced with a new device. Sensor failure is easy to determine. Its failure is most often accompanied by certain symptoms inherent only in non-working DTOZH. What are these signs, read on.

Symptoms of a non-working DTOZH

The malfunction of the coolant temperature sensor can be determined by the following symptoms:

• the error message in the engine on the dashboard;
• difficulty starting a cold engine;
• high engine idle;
• increased fuel consumption;
• engine overheating due to malfunction of the radiator fan.
  

The last malfunction can be caused not only by DTOZH. If the cooling radiator fan does not work , first of all, check its electric drive and the integrity of the wiring. Only after making sure of their operability can we conclude that it is the temperature sensor that is to blame for the engine overheating. In this case, DTOZH may turn out to be both non-working and conditionally working.

DTOZH: malfunctions

Malfunctions of the coolant temperature sensor include:

• violation of the calibration of the working element (thermistor), as a result of which its resistance does not correspond to the stipulated temperature parameters;
• shorting positive contact to ground;
• violation of the tightness of the sensor housing;
• lack of electrical contact on the connector.

As you can see, there are not so many malfunctions in DTOZH. In the first case, the sensor simply begins to lie, misleading the electronic unit. The latter, using false information, will be forced to make the wrong decisions. Hence the difficult start of the engine, and the excessive consumption of fuel, and the untimely inclusion of the radiator fan.

A short circuit in the sensor occurs when its body is deformed or destroyed. This phenomenon is easily determined by the controller, about which it sends a corresponding signal to the instrument panel.

Violation of the tightness of the housing most often also occurs due to mechanical damage to the sensor, less often - due to prolonged use.

If there is no contact on the DTOZh connectors, the controller usually supports the engine in emergency mode, and the radiator fan is in constant mode just in case.

The first three faults cannot be fixed. Here, only the replacement of DTOZH can correct the situation. In the latter case, contact can be restored, which is not difficult. After this, it is necessary to double-check the operability of the cooling system.

Where in the car to look for DTOZH?

You can verify the malfunction or serviceability of the sensor by a simple check. But first, you should learn something about the location of the DTOZH. Where is the coolant temperature sensor in a particular car, it is better to learn from the manual for its operation. The fact is that in different models it can have a different arrangement. Most often, DTOZH is installed on the inlet pipe of the cylinder head cooling jacket or on the thermostat housing.

It is important not to confuse the coolant temperature sensor with the coolant temperature gauge sensor (ARC). The latter also serves to determine the temperature of the coolant, but its data is used solely to inform the driver.

Sensor removal

Check DTOZH provides for dismantling the sensor. To do this, disconnect the negative terminal from the battery and partially drain the coolant. After that, the connector on the DTOZH case is disconnected. The sensor itself is twisted out of the seat with an open-end wrench. The technological hole is closed with a clean cloth during the test to prevent moisture or debris from getting into the cooling system.

How to check DTOZH?

To check the sensor you will need:

• car tester (multimeter);
• an electric kettle or other devices for heating water;
• liquid thermometer.
  

Checking the sensor is to determine the correct calibration of the working element DTOZH. What does it mean? This means that during the test it is necessary to establish how correctly the resistance of the thermistor changes depending on the temperature.

To begin with, the sensor contacts are connected to the probes of the multimeter, observing the polarity. The device is turned on in ohmmeter mode. After this, the DTOZH together with the thermometer is lowered into cold water and their readings are read. Next, the water is heated, continuing to take measurements.

Below is a table for calibrating coolant temperature sensors.

If the resistance indicators of the working element DTOZH differ from those given in the table, the sensor is faulty.

How to replace?

The process of replacing the sensor will not cause any difficulties even for a person who has never been involved in car repairs, especially if the device has already been dismantled for inspection. The only thing to do is to acquire a new DTOZH. The price of coolant temperature sensors, depending on the make of the machine, can vary between 300-800 rubles.

Having bought a DTOZH, all that needs to be done is to first check it in the manner described above (for greater confidence in its performance), and then screw it into the old place and connect the corresponding connector. After this, add coolant, and also connect the ground wire to the battery. Next, we start the engine, warm it up and observe the operation of the cooling system: did the error on the dashboard disappear, did the radiator fan turn on in time, did the engine work evenly, etc.

Useful Tips

1. Before proceeding with the replacement of an inoperative coolant temperature sensor, make sure that the reason is in it.
2. Buy and install DTOZH only that modification, which is provided by the manufacturer of the car.
3. Systematically check the condition of the cooling system and the operability of its individual elements.
4. Pay attention to the coolant temperature. If an error occurs on the instrument panel related to the operation of the cooling system, immediately take measures to eliminate the causes of the malfunction.
5. Never put poor quality coolant or water into the engine. Do not mix antifreeze and antifreeze in one system.