Malfunction of the engine temperature sensor is manifested as a resistance standard. For example, when engine temperature is 75 OS standard resistance is about 290 Ohms. If the sensor has a resistance of 100 Ohms more that the EFI unit "think" that the engine still not fully warmed up, and will give the cylinders more fuel. And this is usually increased engine rpm.
The sensor is tested after removal from the engine. To do this, remove the air cleaner, pour it in the coolant. Then disconnect sensor electrical connector and Unscrew it from the housing.
Lower the engine in a container of water and heat at a temperature of 90 ° C, turn off and leave to cool in the pot. In parallel, temperature control by means of a special device (thermometer) and take readings with the ohmmeter. If performance is approximately 100-700 Ohms, so everything is in order and if not replace the sensor. Also measure the resistance of the sensor at different values of temperature, namely at a temperature of -10 ° C + / -3 ° C - resistance is 8.2 to 10.5 Kω at 20 ° C + / -3 ° C and 2.3-to 2.7 Ohms, and at 80 ° C + / -3 ° C resistance equal to 0,3-0,36 Ohms. If these data fall outside the standards, then the sensor requires replacement.
Check the engine temperature sensor's resistance with other features described in the instruction manual of the sensor. In any case, do not check the sensor circuit directly on the engine without disconnecting it from the control system, since in this case the risk of damage to the electronic control unit.
Basically, the malfunction of the engine temperature sensor very rare and occurs usually on the machines, which age more than 12 years.
Advice 2: How to check the temperature gauge
The pointer of the temperature sensor works. Typically, the sensor temperature of the coolant in the car do not require any maintenance. But often, the motorist may be tempted to doubt the correctness of his testimony. A malfunctioning sensor temperature may cause engine damage, repair of which will result in a tidy sum. In this case, check the correctness of his testimony.
You will need
- a set of tools, tester, hot water, resistor 100 Ohms
Disconnect the connector of the sensor temperature of the coolant at the engine when it is off. Take the resistor on 100 Ohm, and connect it to the sensor connector temperature. Then turn the key turn the ignition on. If the pointer of the temperature normal, the arrow on it should show 90 º C. When doing this engine must be cold. If the arrow on the dashboard does not show anything, ring out the wiring leading to the index temperature. In that case, if the wiring is intact, and the pointer, just replace the device – problem in it.
In that case, if the pointer is working properly, connect the connectors to the sensor temperature of the coolant. Start the engine and allow it to fully warm up. If the pointer of the temperature do not show anything, or it readings do not correspond to the normal temperature of the engine – the problem is the sensor itself, replace it.
There is another way to check the index temperature. Disconnect the car's negative battery terminal. Drain the engine antifreeze to loosening of the sensor it is not raining. The engine should not be hot. Slide the protective sleeve over harness, which fits to the sensor, and disconnect the connector to which it is connected.
The key, gently loosen the sensor, and then remove it from the slot. Take the tester, adjust the mode of operation of the ohmmeter. Connect one contact to the output of the sensor, and the second to his body. The tester should show resistance 700-800 Ohms at room temperature. When immersing the sensor in hot water, its resistance should decrease and as the cooling water, to rise again. If not – the problem is in the sensor. In that case, if the sensor is a whole – pozvanite wiring, and if necessary, change the pointer of the temperature.