CTS sensor DTC problems
Coolant Temperature Sensor can give quite a headache in terms of causal errors. Malfunction of the sensor will affect significantly elevated concentrations of carbon monoxide due to the excessive dosage of fuel. Engine coolant temperature sensor also acts as a resistor. It is usually supplied with voltage of 5V, which drops in the output signal as sensor heats up.
This information will be used by ECU to increase the dosage of fuel until engine reaches the operating temperature. Suppose two situations. Resistor is in a short-circuit, and signal has a constant value of 5V, regardless of engine temperature. The engine will run smoothly until the coolant warms up, when the mixture becomes too rich, and engine starts to run erratically at idling with significantly increased consumption and tendency to stop running.
There is also a quite confusing situation in the ECU processor calculation system. Lambda sensor reads high concentration of carbon monoxide, while the temperature sensor provides a signal that the engine is cold and needs increased fuel dosage. After a certain period of engine running under such conditions, leads to deposition of carbon on the lambda probe, what completely disrupts its reading.
It is quite obvious that chemical process in catalytic converter is also disturbed, and control probe will send negative signal accompanied with few more errors related to fuel pressure, etc. So, in this case also, we read several DTCs but problem lies in only one of them. With a good theoretical knowledge, everyone will first consider the validity of the CTS sensors. How to test CTS sensor?
This information will be used by ECU to increase the dosage of fuel until engine reaches the operating temperature. Suppose two situations. Resistor is in a short-circuit, and signal has a constant value of 5V, regardless of engine temperature. The engine will run smoothly until the coolant warms up, when the mixture becomes too rich, and engine starts to run erratically at idling with significantly increased consumption and tendency to stop running.
There is also a quite confusing situation in the ECU processor calculation system. Lambda sensor reads high concentration of carbon monoxide, while the temperature sensor provides a signal that the engine is cold and needs increased fuel dosage. After a certain period of engine running under such conditions, leads to deposition of carbon on the lambda probe, what completely disrupts its reading.
It is quite obvious that chemical process in catalytic converter is also disturbed, and control probe will send negative signal accompanied with few more errors related to fuel pressure, etc. So, in this case also, we read several DTCs but problem lies in only one of them. With a good theoretical knowledge, everyone will first consider the validity of the CTS sensors. How to test CTS sensor?
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As in previous examples, we will first check the sensor power supply. It is strongly recommended to use the multimeter instead of test lamp which is commonly used in such procedure.
Due to possible incorrect connection, the test lamp may cause a short circuit with very undesirable consequences. If we have, when ignition is on, power supply of 5V or other value specified for particular vehicle, we can perform the sensor testing. The sensor can be tested on the engine, or when taken out.
With the multimeter we shall measure the resistance between two terminals on the sensor, which value, in this case, suppose to be 7000-13000 Ohms when sensor is cold.
By heating the sensor, the resistance must be proportionately reduced to 700-1000 ohms when engine reaches the operating temperature. If there is no difference in the resistance, the sensor is faulty.
Due to possible incorrect connection, the test lamp may cause a short circuit with very undesirable consequences. If we have, when ignition is on, power supply of 5V or other value specified for particular vehicle, we can perform the sensor testing. The sensor can be tested on the engine, or when taken out.
With the multimeter we shall measure the resistance between two terminals on the sensor, which value, in this case, suppose to be 7000-13000 Ohms when sensor is cold.
By heating the sensor, the resistance must be proportionately reduced to 700-1000 ohms when engine reaches the operating temperature. If there is no difference in the resistance, the sensor is faulty.
Why should we test the sensor if DTC shows its obvious failure? Primarily, because reading showed several codes instead of one. Furthermore, the problem does not necessarily lie in the sensors failure. Insufficient coolant volume will affect the faulty sensor response. In such cases, the heated coolant will not heat the sensor, but only a formed steam to which the sensor will not react as it would immersed in the liquid.
Another problem may lie in the thermostat failure, which does not close the fluid flow completely and thereby preventing the engine to reach the operating temperature. Therefore, if we want to be absolutely sure that we know we are doing and prevent possible unnecessary investment, it is advisable to test the sensor. Presented sketches show the CTS sensor test procedure.
Another problem may lie in the thermostat failure, which does not close the fluid flow completely and thereby preventing the engine to reach the operating temperature. Therefore, if we want to be absolutely sure that we know we are doing and prevent possible unnecessary investment, it is advisable to test the sensor. Presented sketches show the CTS sensor test procedure.
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The last sketch shows the sensor test when immersed in a heated fluid. On the chart we see how resistance increases when sensor is heated. This is the opposite situation from previous one where the resistance decreases by heating the sensor. In any case, the resistance changes its value by heating the sensor, either by reducing or increasing the resistance value. Just because of such different values, it is very useful to use the literature for particular vehicle, so that we know what we are looking for. Such information is quite helpful if we are performing test by short connecting terminals on the connector.
Suppose we have a case of excess fuel as described before. Knowing that resistance is reduced by heating the sensor, we can bridge the two terminals on the sensor connector and see the effect. How? If warming reduces the resistance of the sensor, the value of the sent signal to the ECU, at engine operating temperature, will be 5V. The same values of the signal we shell get by short connecting two terminals.
In other words, if the sensor was faulty, leading the full voltage output to the engine computer, we provide information of the engine operating temperature achievement. Taking into account this information, the ECU will reduce the dosage provided for a cold engine and switch on the Closed Loop, when it relies on the Lambda probe signals.
Suppose we have a case of excess fuel as described before. Knowing that resistance is reduced by heating the sensor, we can bridge the two terminals on the sensor connector and see the effect. How? If warming reduces the resistance of the sensor, the value of the sent signal to the ECU, at engine operating temperature, will be 5V. The same values of the signal we shell get by short connecting two terminals.
In other words, if the sensor was faulty, leading the full voltage output to the engine computer, we provide information of the engine operating temperature achievement. Taking into account this information, the ECU will reduce the dosage provided for a cold engine and switch on the Closed Loop, when it relies on the Lambda probe signals.