Temperature indicator with diagnostic function. How to check the temperature gauge Universal digital engine temperature indicator

SPECIFICATIONS

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Universal engine temperature indicator with diagnostic function

The indicator is designed to display the temperature of the coolant in digital form, as well as display and erase diagnostic codes that occur when malfunctions occur in the engine and transmission control system. The indicator is used in vehicles equipped with a digital information bus CAN.

ATTENTION! The indicator does not work on cars of the VAG group (Volkswagen, Audi, Skoda, Seat).

SPECIFICATIONS

LIST OF SUPPORTED VEHICLES

The list of cars will increase as tests are carried out.

ATTENTION! The indicator does not work on cars of the VAG group.

METHOD OF CONNECTING TO THE VEHICLE

The coolant temperature is displayed on the indicator for a few seconds after the ignition is switched on. The indicator periodically sends a request to the CAN bus and updates the temperature readings.

The engine and gearbox are diagnosed when the ignition is turned on, the indicator displays the number of stored errors in the EXX format, where XX is the number of errors. Further, the running line displays the error codes. The code consists of five characters: one letter and four numbers. Decryption codes can be found on the Internet. After displaying all errors, the indicator will show the temperature of the engine.

To erase the codes from the memory of the car's blocks, you must turn off the ignition, then press the accelerator pedal to the maximum, turn on the ignition and wait for the "clr" error erasing notification to appear on the indicator. If the errors persist, repeat the erasing procedure.

Motors that operate in high load modes (constant driving at high speeds, on the original engine, etc.).

As for the coolant temperature, it must be constantly monitored on any power unit, and accurate information will help to avoid. At the same time, it is important to take into account that the standard sensor on many cars gives a very mediocre idea of ​​the degree of coolant heating.

Also, some models straight from the factory are completely devoid of an engine temperature gauge on the dashboard. In such cases (when there is no indicator or it shows only average values), drivers usually install a third-party engine temperature sensor (the digital analogue provides more accurate data compared to the standard solution). Let's look at this device in more detail.

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Engine temperature indicator: features

Let's start with a common situation. For example, a car has a standard temperature gauge, but on such devices the scale may often not have calibrations, and the engine’s operating temperature needle in the middle position displays the real picture only conditionally.

At the same time, during operation, the driver notices that if the middle on the scale is the norm, then in various situations the arrow can rise noticeably higher (for example, in traffic jams). It would seem that the motor is overheating.

Naturally, the movement of the car immediately stops, the owner hurries to turn off the engine and open the hood. However, upon inspection of the unit is not. Next, a restart is performed and it turns out that it does not even turn on, although the device is operational.

When feeling, the upper radiator pipe has an acceptable temperature, antifreeze does not “press” anywhere, the lower pipe can be completely cold, etc. A further check of the coolant level and the condition of the coolant itself also shows that the liquid is normal, the interior heater (stove) is working normally, there are no air locks in the system, it is also in good order.

It also happens that if you let the engine cool down completely, then start the engine and warm up the power unit to operating temperatures, this process can take a long time (judging by the indicator on the instrument panel). At the same time, you can notice that although the arrow has only slightly risen, and the radiator fan is already working, the lower radiator pipe is warm, etc.

If we consider that everything is in order with the fan and the cooling system, then the signs described above indicate a large error or problems with the engine temperature gauge. It is quite obvious that in such a situation it becomes difficult to understand when the engine reaches operating temperatures, whether the internal combustion engine is overheating, how much it is necessary to warm up the engine before a trip, etc.

At the initial stage, many drivers begin to look for the cause. Some at once:

• regular temperature sensors on the engine and in the dashboard are checked;
• the wiring is ringing, etc.

In some cases, the problem can be solved, while in others it is still not possible to achieve the correct operation of the standard temperature indicator. The fact is that often the culprit is the control electronic modules, which give a certain failure.

Changing such modules is expensive and impractical. In this situation, a digital engine temperature indicator is a qualitative solution. Such an electronic sensor has a quite reasonable cost (on average, from 15 to 55 USD), it is relatively easy to connect and install. The range of measured temperatures is also very wide (on average, from -65 to +240).

Note that on different types of internal combustion engines, the installation features may differ slightly.

1. The device is usually powered by the ignition switch.
2. The digital panel is installed in a convenient place in the car.
3. As for the sensor itself, for accurate readings it must be immersed in coolant.

In other words, the device must be screwed into the block or cut into the pipe. To do this, some drivers replace the standard temperature sensor by simply screwing in a new one instead. However, this cannot be done on cars with for a number of reasons.

The fact is that the controller receives readings about the coolant temperature. In this case, it is necessary to separately implement the installation of the digital indicator sensor, since it is strongly not recommended to remove the standard temperature sensor from the system.

Summing up

Now a few words about practical operation. If the sensor is installed correctly, then the error of its readings will be minimal (no more than 1 degree Celsius). The presence of this device in the car allows you to constantly monitor the temperature of the engine and coolant.

At the same time, it should be noted that the indicator can also be used to check the operation of the thermostat and the declared thermostating temperature. If it is simple, for example, the thermostat should open at a temperature of 85 degrees.

The engine first warms up to medium temperatures, then you can take hold of the radiator pipe. When it gets hot, it will indicate the thermostat is opening. At the same time, the declared thermostat opening temperature should also be displayed on the indicator, that is, all the same 85 degrees (adjusted for error). Also, among the advantages, one should highlight the possibility of accurately monitoring the temperature of not only a hot, but also a cold motor.

Finally, we note that the most crucial moment during installation can be considered the installation of the sensor itself on the engine. The device must be sealed. Also, increased requirements are put forward to the reliability of its fastening. It is important to avoid even the slightest leakage of antifreeze from the cooling system, which can occur precisely at the installation site of the digital engine temperature sensor.

Read also

The device, principle of operation and location of the engine temperature sensor. Distinctive features of various types of internal combustion engine temperature sensors.

The cooling system is one of the most important elements of a car. After all, if a coolant leaks or a violation of its circulation occurs, the engine instantly overheats and fails if it is not turned off in time. In this regard, it is advisable to monitor this system. Although any car has coolant temperature sensors, they will never tell you about a leak. After all, if the liquid flows out, then perhaps a breakdown has occurred somewhere, which urgently needs to be fixed. Thus, the device proposed by the author will be a great addition to any car that will make it more reliable and save your nerves.

Materials and tools:
- two LEDs (green and red);
- printed circuit board;
- JAL compiler;
- PIC16F88 microcontroller;
- wires;
- resistors, capacitors (the value is indicated on the diagram);
- soldering iron with solder;
- fuse.

Step one. Electronic circuit
The indicator works on a PIC16F88 type microcontroller, JAL software is used for it. The firmware for the indicator is attached to the article. The whole system has two LEDs, one red and one green. When the coolant level in the expansion tank is normal, the light will turn green. If it falls below the set norm, the red light will turn on.
The system should only turn on when the ignition switch is turned on, and it should only be connected through a fuse.

Now all that remains is to connect and wire everything. The wires must be laid so that they do not touch the engine elements and do not hang out. They need to be wound with electrical tape to a common wiring harness or fixed with plastic ties.
The board is hidden in the console, and the LEDs can be displayed anywhere at your discretion.

Step four. Device testing
When the ignition in the car is turned off, the LEDs should not flash, if they flash, then the system is connected to the wrong fuse. When the ignition is turned on, the green LED should flash, this will indicate that the sensor is immersed in coolant and the system is working properly. If the lights aren't on, it's possible that +12V isn't coming into the system. You also need to check to see if ground is present. Also, the LEDs may not light up for the reason that their polarity is incorrectly selected.

One of the most important systems in a car, necessary for the normal operation of the engine, is the cooling system. Its task is to maintain the optimum temperaturenecessary for the operation of the motor. One of the essential elements of this system is the coolant temperature sensor. About him and will be discussed today.

During the combustion of fuel, a lot of heat is released, and only 30-35% of this heat is used to do work. About half of the remaining amount flies out with the exhaust, and a cooling system is needed to remove the rest, otherwise the engine will overheat.
The vast majority of modern cars have a liquid cooling system. Principle of operation: a special liquid (antifreeze) takes heat from hot parts and releases it into the environment. This ensures the constancy of the thermal regime, necessary for the normal operation of the motor, as well as uniform heating if the motor was cold.
But in order for antifreeze to perform its task correctly and efficiently, a number of special devices are needed. In order to maintain the operating temperature of the coolant (that is, the one at which engine operation is optimal), you need to know how many degrees it is at the moment.

coolant temperature sensor

This task is performed by the coolant temperature sensor.

Principle of operation

The principle of operation of all coolant temperature sensors (coolant) is based on the change in the resistance of a special semiconductor element (thermistor) from temperature. The hotter, the less resistance, and vice versa.

How it works

If the engine is injection, then the temperature values ​​\u200b\u200bare needed by the engine controller (ECU, electronic control unit) in order to control the cooling fan and the operation of the motor. A constant (reference) voltage (5 volts) is applied to the coolant temperature sensor, current passes through it, and the voltage drops. The greater the resistance of the coolant temperature sensor, the higher the voltage on it, the lower the voltage will be at the output. The controller measures it and, based on the program embedded in it, calculates the temperature. Two wires are connected to such a sensor: one current flows from the computer, the other goes back.
If your car has a digital coolant temperature gauge, then it takes its readings from the control unit. Usually he shows numbers, symbols (number of "sticks"), or signal lights are used.
But sometimes an additional coolant temperature sensor is installed if the coolant temperature indicator is arrow. Usually one wire goes to it. The deflection of the arrow depends on the strength of the current flowing through the thermistor, which also depends on its resistance. Cold - high resistance - low current - the arrow is tilted to the left, and vice versa.

Coolant temperature gauge

On carbureted cars, and rarely on injectors, there is also a separate fan switch sensor. It does not measure anything, but only turns on the cooling fan at a certain temperature.

Wiring diagram for coolant temperature sensor

Two-wire: It is connected to two outputs of the ECU, one of which is supplied with a reference voltage, and the second one measures the voltage.
Single wire: it is supplied with a current flowing through a device showing the temperature of the coolant, the role of the second wire is performed by its body attached to the "mass" (for example, a metal part of the engine). If its body does not come into contact with metal, a second wire is used to connect to ground.

Wiring diagram for coolant temperature sensor

How do you know if the sensor is bad?

Symptoms of a malfunctioning coolant temperature sensor the following:

1. The coolant temperature gauge does not work, or does not show the actual coolant temperature.
2. Fluctuating coolant temperature.
3. Continuously running cooling fan (if injection engine).
4. The "Check Engine" warning light is on (if an injection engine).
5. The car overheats, “boils” (steam from under the hood, strong gurgling in the expansion tank), but the fan does not turn on.

The cause of these events can be not only its failure, but also other malfunctions (wiring, connections, etc.). Therefore, the injector must first be diagnosed. If it is impossible to make a diagnosis, or you have a carburetor engine, then immediately proceed to checking the coolant temperature sensor

Where is the coolant temperature sensor

The location of the coolant temperature sensor varies on different motors. The most common installation locations are as follows:

• Engine (cylinder block, or block head);
• Branch pipe of the cooling system, departing from the engine;
• Thermostat;
• Radiator.

To search for it on your car, use special literature, search the forums for your model, thematic sites.

How to check the coolant temperature sensor

Since the principle of operation is a change in resistance, the most accessible way to check is to measure this parameter. To do this, you will need any tester, multimeter, even the simplest Chinese one, the main thing is that you can measure MegaOhms, resistance.
The test can be carried out without removing the sensor from the vehicle. But for this you need to know how many degrees are inside the cooling system. The easiest way is to wait until the temperature of the antifreeze becomes equal to the street temperature. 6-8 hours after the engine has stopped, if it has warmed up. If it's cold outside and the motor is large, then perhaps more.
When you are sure that there are as many degrees in the coolant as in the environment, you need to:

1. Disconnect the terminal from the "minus" of the battery, as before any repair related to the electrician.
2. Find a sensor. Sometimes this will require dismantling any parts.
3. Disconnect wiring.
4. Set the resistance measurement limit to 10,000 ohms on the multimeter (if the temperature is less than 0, then an even greater limit).
5. Attach the multimeter probes to the sensor leads (if there is one lead, then to it and to the case).
6. Compare the displayed value on the screen (scale) of the device with the data in the table below.

Dependence of the resistance of the coolant temperature sensor on temperature

If the measured resistance is very different from the table, most likely the part is faulty. For a more accurate check, you will need to remove it.
It is possible that your model has a sensor with different characteristics. Specify information.

How to remove the sensor

Mounting may be different, so, again, look for information on a specific car. But most often it just twists along the thread. Then its body has a hexagonal shape.
The sequence of actions is as follows:

1. Disconnect the "negative" terminal of the battery.
2. Find a sensor.
3. Disconnect the wiring.
4. Partially drain the antifreeze (if the sensor is high enough, you can skip this, check for a specific model). You can also avoid this if you find a plug (for example, a suitable bolt) and quickly put it in place of the removed part.
5. Unscrew the sensor (if it is threaded), or unfasten it in another way provided by the design.

Complete sensor test

For this, you will need, again, a multimeter and a thermometer that can be submerged in water and shows up to 100 ° C. Order of execution:

1. Connect the multimeter wires to the sensor contacts.
2. Lower the part to be checked and the thermometer into a container of water.
3. Heat the water by monitoring the temperature and readings of the multimeter.

Checking the coolant temperature sensor

As you have already seen from the table, the resistance of the sensor varies with temperature. If they match the table, he's fine. When changing the resistance values, there should not be sharp jumps - this is also a sign of a malfunction. If you do not have a suitable thermometer, you can only test with boiling water, i.e. at 100°C. The resistance in this case should be approximately equal to 180 ohms.

How to change the coolant temperature sensor

If you did not remove the sensor to check, then you need to do this operation. Purchase a spare part. Buy only original parts, or from trusted companies, be sure to keep receipts.

The percentage of marriage for these spare parts is very large for unscrupulous firms.

The best option would be to check the sensor in the above way at the time of purchase or at the first opportunity.
Install the new sensor in place and connect the wires. The symptoms should disappear. If this did not happen, either the problem is not only in it, or the sensor is defective, which, in principle, should have been revealed during the check.

Conclusion

The coolant temperature sensor is a small but important detail. If it malfunctions, the engine is threatened with overheating, which can result in serious consequences. So at the first suspicion of a malfunction, find out its cause and eliminate it as soon as possible.

The temperature gauge is powered by a sensor. As a rule, coolant temperature sensors in a car do not require any maintenance. But often a motorist has doubts about the correctness of his testimony. A faulty temperature sensor can cause engine damage, the repair of which will result in a tidy sum. In this case, check the correctness of his testimony.

You will need

tool kit, tester, hot water, 100 ohm resistor

Sponsored by the placement of P&G Articles on the topic "How to check the temperature gauge" How to raise the temperature of the engine How to replace the coolant temperature sensor Why the engine is running hot

Instruction

Disconnect the engine coolant temperature sensor connector while the engine is off. Take a 100 ohm resistor and connect it to the temperature sensor connector. After that, turn the key to turn on the ignition. If the temperature gauge is working, the arrow on it should show 90 ° C. The engine must be cold during this work. If the arrow on the dashboard does not show anything, ring the wiring leading to the temperature gauge. In the event that the wiring is intact, and the pointer does not work, simply replace this device - the problem is in it.

If the pointer is working properly, connect the connectors to the coolant temperature sensor. Start the engine and let it warm up completely. If the temperature gauge does not show anything, or its readings do not correspond to normal engine temperature, the problem is in the sensor itself, replace it.

There is another way to check the temperature gauge. Disconnect the negative battery terminal on the vehicle. Drain the antifreeze from the engine so that it does not spill when unscrewing the sensor. The engine must not be hot. Slide the protective cambric off the harness that fits the sensor and disconnect it from the connector to which it was connected.

Using a wrench, carefully loosen the sensor, and then unscrew it from its socket. Take the tester, adjust it to the ohmmeter mode. Attach one contact to the output of the sensor, and the second to its body. The tester should show a resistance of 700-800 ohms at room temperature. When the sensor is immersed in hot water, its resistance should decrease, and as the water cools, increase again. If this does not happen, the problem is in the sensor. In the event that the sensor is intact, call the wiring, and, if necessary, change the temperature gauge.

How simple

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A variety of signaling devices are used to monitor the operation of an internal combustion engine. We propose to consider how the coolant temperature sensor works, how it is checked and replaced if it is faulty.

What it is

The standard coolant sensor is a device that is used to measure the antifreeze found in an internal combustion engine. The fixed sensor parameters are returned by means of signals to the engine control unit, which in turn uses this data to adjust the required amount of fuel and a certain ignition angle.

In some car models, the signaling device can be used to switch to an electric ventilation cooling system. Let's say this is how the car coolant temperature sensor works in the VAZ-1117 (and number 1119) Lada Kalina, Lada Priora and Grant, Lanos, Toyota Camry (Toyota).

Photo - coolant temperature sensor VAZ 2010

On many foreign cars, the instrument readings are also displayed on the dashboard. For example, in Volkswagen Golf (Volkswagen Golf), Subaru (Subaru), Mazda (Mazda), Opel Vectra (Opel Vectra) and Passat (Passat), BMW (BMW), Ford Focus (Ford Focus), Daewoo Nexia (Daewoo Nexia) , Fiat (Fiat), Audi (Audi) and others.

As the temperature of the sensor is measured, its resistance level may change. Exist two kinds such sensors depending on the change in resistance:

1. Sensors with a negative temperature coefficient, work on the principle: internal resistance decreases with increasing temperature and vice versa;
2. PTC sensors. As the temperature rises, they increase the resistance.

Almost all cars have signaling devices with a negative coefficient. There are negative coolant temperature sensors in Gazelle, GAZ, MAZ, Kamaz, Mercedes, Nissan, Niva, Mitsubishi, OKA, Peugeot, Volvo, Renault Logan (Renault Logan), OPEL Astra (Opel Astra), Geely, ZMZ.

Photo - temperature sensor

The principle of operation of the sensor

The vehicle control unit sends a regulated voltage (9 volts) directly to the coolant temperature gauge sensor. Depending on the drop in voltage at the contacts of the signaling device, the resistance will drop, which will immediately fix the control unit.

In such a case, the automotive computer or mechanical system will be able to calculate the engine temperature, and then (using data from other instruments) apply lookup tables to perform adjustments to the engine actuators, i.e. change the level and flow of fuel or the ignition timing.

Photo - diagram of the coolant temperature sensor

The resistance of the coolant sensor is very dependent on external factors. This is the air temperature outside the car, various features of the drive. For the most correct operation of the signaling device, you need to use the coolant recommended for a certain time of the year, it is expensive, but prolongs the life of your car.

Video: checking the engine temperature sensor

Sensor replacement

To start repairing the coolant sensor, you need to determine its location. Most often it is installed near the thermostat or radiator, in some cases the on-board computer uses readings from both sensors or one of them, depending on the brand of car and its model. For example, this is how the sensor is located in Renault, Chevrolet, Citroen, Skoda, Chery, KIA, Subaru Impreza.

There are several ways to help you find out that the sensor needs to be changed. If you have all the other systems in your car working, then on the dashboard you will report a malfunction using a light signal. If the car has computer control, then it will be possible to determine the problem by decoding the combination on the monitor.

Photo - temperature sensor on the dashboard

Depending on the year of manufacture of the car, as well as its brand, many motorists note an increase in fuel costs for the engine. But at the same time, you need to understand that you can’t define a diesel engine like that (UAZ, PAZ and others). If you have a mechanic, and not a computer control system, then here signals what you need to buy a new coolant temperature sensor:

1. The car began to consume more fuel than usual;
2. When the car starts and the engine reaches its maximum temperature, it stalls;
3. There were problems with the launch;
4. Black smoke comes out of the muffler pipe.

Consider how the G62 type coolant temperature sensor is replaced on a Kia Sportage with a 2-liter engine. A similar instruction is also useful when repairing Acura, BMW, Buick, Chevrolet, Ford, Toyota, Volkswagen, VAZ 2110/2112 injector, Renault Grand Scenic and others.

Photo - different coolant temperature sensors

In this model, if the coolant sensor breaks, an alarm 117 is received, which indicates that further operation of the device is impossible and a new signaling device must be installed. In Chevrolet, PO118 is a high signal. General scheme of work looks like that:

Advice from motorists on the forums: if for some reason you cannot immediately understand the coolant temperature sensor in the event of a breakdown, then you can connect an additional one instead (such a connection may differ slightly from the main one in terms of temperature).

Magnetoelectric coolant temperature gauge[rice. 1, A] includes a TM100 sensor and a UK105 ratiometric receiver. The main element of the sensor is a semiconductor thermistor (1). The thermistor is located in the cylinder (2). By means of the spring (3) contact of the thermistor with the "mass" (cylinder) and output (4) is achieved. The paper cartridge (5) isolates the side surface of the thermistor and spring from the cylinder body. As the temperature rises, the resistance of the thermistor decreases. In the receiver, three coils (K 1), (K 2) and (K 3) are wound on two plastic fixed frames (9). Coils (K 1) and (K 2) consist of 850 turns of PEL wire (diameter 0.1 mm) each. Their resistance is 100 ohms. The coil (K 3) consists of 400 turns, and its resistance is 42 ohms. The temperature compensation resistor (R tk) is made of PEVSOK constantan wire (diameter 0.1), and its resistance is 100 ohms. Coils (K 1) and (K 2) are wound on one frame in such a way that the current flows in them in opposite directions and the magnetic fluxes are directed one against the other.

Rice. 1. Temperature gauges and alarms. Schemes of a magnetoelectric coolant temperature gauge.

A) - General;

B) - Electrical;

C) - Electrolyte temperature indicator sensor in the storage battery;

1) - Output terminals;

2) - Insulating bushing of clamps;

3) - Sealing gasket;

4) - Gas outlet;

5) - Housing;

6) - Polyethylene cylinder;

7) - Brass cylinder;

8) - Paper cartridge;

9) - Contact spring;

10) - Brass cup;

11) - Thermistor;

Alarm for emergency coolant temperature.

D) - Scheme of inclusion;

E) - Sensor ТМ111;

1) - Conclusion;

2) - Insulator;

3) - Adjusting screw;

4) - Contact;

5) - Housing;

6) - Contact;

7) - Clamping washer;

8) - Bimetallic plate;

9) - Plug terminal.

O the winding of the coil (K 3) is at right angles to the windings of the coils (K 1) and (K 2). A movable permanent magnet (8), which is mounted on the arrow axis (6), is placed in the annular area between the coil pads. When the power is turned on by means of the ignition switch (13), the battery current flows in two parallel branches:

1) - through the coil (K 1) and thermistor (1);

2) - through coils (K 2) and (K 3) and a temperature compensation resistor. In this case, there is a change in the strength of the current that passes through (K 1) and the thermistor, in accordance with the change in resistance and temperature of the thermistor, while the current of the other branch remains approximately constant. The resulting magnetic flux of the three coils, when interacting with a permanent magnet, sets the pointer in relation to the scale to a position that corresponds to the ambient temperature. After the power supply is turned off - the pointer under the influence of a permanent magnet (12) is to the left of the mark (40 degrees Celsius). The steel magnetic circuit (7) is also a screen that protects the drive from the influence of extraneous magnetic fields on it. In the slot (10) moves the bent end of the limiter (11) of the angle of rotation of the arrow.

Alarms for emergency coolant temperature serve to warn drivers of a critical increase in temperature in the cooling system. The signaling device includes a sensor mounted in the upper tank of the radiator [Fig. 1, D] and a control lamp (5), which is located on the instrument panel. On the body (3) of the sensor, a bimetallic plate (3) is isolated from the "mass", closed by means of a brass cartridge (1). The fixed end of the plate is connected to the output terminal, and a contact is attached to the moving end (on the side of the inactive layer). The fixed contact is soldered to the adjusting screw (4), which is connected to the ground (housing). As long as the coolant temperature remains below the specified limit, the signaling device contacts are in the open state, and the light is off. With an increase in temperature, the deformation of the bimetallic plate and the convergence of the contacts occur. The closing of the contacts and the switching on of the signal lamp occurs when the temperature reaches the value to which the sensor is adjusted. The TM29 sensors (ZIL-130 car), TM104-T (GAZ-53A car) turn on the lamp at 105-108, 112-118 degrees. Celsius, respectively, and MM7, TM111 (KamAZ car) and MM7-T - at 92-98 and 104-107 degrees. Celsius. The RS403 sensor, mounted in the fourth cylinder head of the D-37M air-cooled engine, turns on a signal lamp at a temperature of 160-175 degrees. Celsius. If during the test it turns out that the switch-on temperature does not match the specified one, then the sensor should be disassembled and the gap adjusted.