We independently change the antifreeze temperature sensor on the VAZ 2107

Any internal combustion engine must be cooled in a timely manner. Without this, his normal work is simply impossible. This rule is also true for VAZ 2107 engines. The most problematic device in the cooling system of this car is the sensor that records the temperature of the antifreeze in the main radiator. It crashes frequently. Luckily, you can replace it yourself. Let's figure out how best to do this.

The purpose of the temperature sensor VAZ 2107

The sensor controls the temperature of the antifreeze in the main cooling radiator of the VAZ 2107 and transmits a signal to the dashboard. In its lower left corner there is an arrow pointer for the temperature of antifreeze.

The sensor showing the temperature of the coolant VAZ 2107

If the temperature has risen above 95 degrees, this means only one thing: the cooling system is not doing its job and the engine is close to overheating.

Temperature sensor VAZ 2107 transmits a signal to the dashboard

Antifreeze temperature sensor device

Over the years, different types of temperature sensors were installed on VAZ 2107 cars. The earliest VAZ 2107 models had electromechanical sensors. Later they were replaced by electronic sensors. Consider the design of these devices in more detail.

Electromechanical temperature sensor

Electromechanical sensors have a massive steel case with thick walls, providing a more uniform heating of the device. In the case there is a chamber with ceresite. This substance is mixed with copper powder, and it responds very well to changes in temperature. The ceresite chamber of the sensor is closed by a very sensitive membrane connected to the pusher. When hot antifreeze heats up the sensor body, the ceresite in the chamber expands and begins to press on the membrane. The membrane moves up the pusher, which closes the system of moving contacts. The signal thus obtained is broadcast to the dashboard, informing the driver that the engine is overheating.

The device of the electromechanical temperature sensor VAZ 2107

Electronic temperature sensor

Electronic temperature sensors are installed only on new VAZ 2107. Instead of a membrane and a chamber with ceresite, the electronic sensor has a sensitive thermistor. As the temperature rises, the resistance of this device changes. These changes are fixed by a special circuit, which transmits a signal to the dashboard.

Electronic sensor device VAZ 2107

Location of the antifreeze temperature sensor on the VAZ 2107

The temperature sensor is screwed into the main cooling radiator of the VAZ 2107. This arrangement is quite natural: this is the only way the sensor can directly contact boiling antifreeze. One nuance should also be noted here: on the early VAZ 2107 models, the temperature sensor also performed the function of a plug that closed the antifreeze drain hole. In new VAZ 2107 cars, the drain hole is closed with a special plug, and the temperature sensor is screwed into its own, separate socket.

In older VAZ 2107 models, the temperature sensor also served as a plug

Temperature sensor malfunctions

There are two reasons why the sensor may not transmit a signal to the dashboard. Here they are:

• the fuse responsible for the temperature sensor has blown (the sensor itself may be in good condition). To understand that the problem is in the fuse, the driver will have to look under the steering column, into the safety block of the car. A blown fuse will be immediately visible: it usually melts slightly and turns black;
  

  Sometimes the sensor does not work due to a blown fuse VAZ 2107
• the temperature sensor burned out. As a rule, this happens due to a sharp voltage drop in the vehicle's on-board electrical network. The cause of such a jump may be a short circuit in the wiring. The fact is that the insulation of wires on the VAZ 2107 has never been of high quality. Over time, it becomes unusable, begins to crack, which eventually leads to a short circuit.

Checking the VAZ 2107 temperature sensor

To carry out the check, we need the following tools:

• household multimeter;
• a container with water;
• household boiler;
• thermometer;
• temperature sensor removed from the machine.

Check sequence

1. The sensor is lowered into the prepared container so that its threaded part is completely under water.
2. A thermometer and a boiler are lowered into the same container (at the same time, you need to make sure that these tools do not come into contact with each other).
3. The contacts of the multimeter are connected to the contacts of the sensor, the multimeter itself is configured to measure resistance.
4. The boiler is plugged into the socket, water heating starts.
5. When the water heats up to a temperature of 95 degrees, the sensor resistance shown by the multimeter should disappear. If this happens, the sensor is OK. If at the above temperature the resistance on the multimeter does not disappear, the sensor is faulty and needs to be replaced.

Video: checking the antifreeze sensor

Check the temperature sensor coolant.

Replacing the antifreeze sensor on the VAZ 2107

First of all, it should be said that the temperature sensors on the VAZ 2107 cannot be repaired. The reason is simple: this device lacks parts and materials that the driver could purchase and replace on their own. In addition, the body of the temperature sensor is non-separable, so it’s simply impossible to get to the insides of this device without breaking it. Here's what you need to replace:

• new temperature sensor VAZ 2107;
• socket head 30 with a long knob (or a regular candle key);
• container for draining the coolant.

Sequence of operations

1. The car is placed on a viewing hole or on a flyover. A container is placed under the drain hole, the plug is unscrewed, the antifreeze is drained.
   

   A small basin is ideal for draining antifreeze from a VAZ 2107
2. Contact wires are removed from the sensor. They must be carefully pulled towards you.
   

   The red arrow shows the contact cap of the VAZ 2107 sensor
3. The sensor is unscrewed with a socket head by 30 (it should be remembered that there is a very thin sealing ring under the sensor, which can be easily lost).
4. A new sensor is screwed in place of the unscrewed sensor (moreover, when screwing in a new sensor, one should not apply too much force, especially if the knob at the end head is very long: the thread in the sensor socket is easily torn off).
5. The cap with contact wires is put back on the sensor, new antifreeze is poured into the expansion tank.

Video: replacing the coolant sensor on the VAZ 2107

Temperature sensor replacement!

Important nuances

There are several important points that cannot be ignored. Here they are:

• the above sequence of replacing the sensor with a complete drain of antifreeze is not always used. Experienced motorists do it easier: unscrew the faulty sensor, then clamp the drain hole with your finger. This action requires a fair amount of skill. But even if you do everything very quickly, part of the antifreeze will inevitably spill out and you still have to add it;
  

  Sometimes motorists do not drain antifreeze from the VAZ 2107 when replacing the sensor
• When going to the store for a new temperature sensor, you should remember: on sale now you can find both electromechanical and electronic temperature sensors. It is better to choose electronic ones, despite the fact that they are more expensive than electromechanical ones (a good electronic sensor costs 500 rubles, and an electromechanical one costs 300 rubles). The logic of choice is simple: the fewer moving parts in the sensor, the longer it will last.

So, replacing the temperature sensor is not a super difficult task. Even a novice motorist will cope with it, if at least once in his life he held a wrench in his hands. By exactly following the steps outlined in this manual, the car owner will be able to save about 700 rubles. This is how much it costs to replace the temperature sensor in a car service.