Detection methods of common faults of the hottest

2022-08-10
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Detection method of common faults of oxygen sensor

detection method of common faults of oxygen sensor:

1. Check the resistance of oxygen sensor heater. Unplug the harness plug of the oxygen sensor, and measure the resistance between the heater terminal and the grounding terminal in the oxygen sensor terminal with the resistance gear of the multimeter. The resistance value is Ω (refer to the specific model manual). If it does not meet the standard, replace the oxygen sensor

2. Measurement of oxygen sensor feedback voltage. When measuring the feedback voltage of the oxygen sensor, unplug the harness plug of the oxygen sensor, draw a thin wire from the feedback voltage output terminal of the oxygen sensor according to the circuit diagram of the vehicle model, and then insert the harness plug. When the engine is running, Measure the feedback voltage from the outgoing line (for some models, the feedback voltage of the oxygen sensor can also be measured from the fault detection socket. For example, the series cars produced by Toyota Motor Company can directly measure the feedback voltage of the oxygen sensor from the OX1 or ox2 terminals in the fault detection socket, which is at the same time at the historic intersection of the new round of scientific and technological revolution, the tide of industrial reform and the accelerated transformation and development mode of China). When detecting the feedback voltage of the oxygen sensor, it is best to use a pointer multimeter with low range (usually 2V) and high impedance (internal resistance greater than 10m Ω). The specific detection methods are as follows:

1) warm up the engine to the normal operating temperature (or run at the speed of 2500r/min for 2min after starting)

2) connect the negative lead of the voltage gear of the multimeter to E1 or the negative pole of the battery in the fault detection socket, and the positive lead to OX1 or ox2 Jack in the fault detection socket, or to the No. | outlet on the harness plug of the oxygen sensor

3) keep the engine running at a speed of about 2500r/min, check whether the voltmeter pointer can swing back and forth between V, and record the number of times the voltmeter pointer swings within 10s. Under normal circumstances, with the progress of feedback control, the feedback voltage of the oxygen sensor will constantly change around 0.45V, and the number of changes of the feedback voltage within 10s should not be less than 8 times. If it is less than 8 times, it indicates that the oxygen sensor or feedback control system is not working normally, which may be caused by carbon deposition on the surface of the oxygen sensor, which reduces the sensitivity. In this regard, the engine should be operated at a speed of 2500r/min for about 2min to remove carbon deposits on the surface of the oxygen sensor, and then check the feedback voltage. If the voltmeter pointer changes slowly after clearing the carbon deposit, it indicates that the oxygen sensor is damaged or the computer feedback control circuit is faulty

4) check whether the oxygen sensor is damaged. Unplug the harness plug of the oxygen sensor, so that the oxygen sensor is no longer connected with the computer, and the feedback control system is in the open-loop control state. Connect the positive probe of the multimeter voltage range directly to the oxygen sensor feedback voltage output terminal, and the negative probe is well grounded. Measure the feedback voltage when the engine is running. First disconnect the positive crankcase ventilation pipe or other vacuum hoses connected to the intake pipe to artificially dilute the mixture. At the same time, watch the voltmeter, and the pointer reading should drop. Then connect the disconnected pipeline, unplug the connector of the water temperature sensor, and replace it with a K Ω resistance. However, the maximum stress that does not deviate from the linear relationship between stress and strain is the water temperature sensor that changes with the accuracy of the measuring instrument. Artificially form a concentrated mixture. Watch the voltmeter at the same time as the energy and power industries, and its pointer reading should rise. The concentration of the mixture can also be changed by suddenly pressing or releasing the accelerator pedal. When the accelerator pedal is suddenly pressed, the mixture becomes thicker and the feedback voltage should rise; When the accelerator pedal is suddenly released, the mixture becomes diluted and the feedback voltage should drop. If the feedback voltage of the oxygen sensor does not change as described above, it indicates that the oxygen sensor has been damaged. In addition, when using the above method to detect titanium oxide oxygen sensor, if it is a good oxygen sensor, the voltage at the output end should fluctuate up and down with 2.5V as the center. Otherwise, the sensor can be removed and exposed to the air, and its resistance value can be measured after cooling. If the resistance value is large, the sensor is good, otherwise the sensor should be replaced

5) check the appearance color of oxygen sensor. Remove the oxygen sensor from the exhaust pipe, and check whether the vent hole on the sensor housing is blocked and whether the ceramic core is damaged. If it is damaged, replace the oxygen sensor. The fault can also be judged by observing the color of the top part of the oxygen sensor:

① light gray top: This is the normal color of the oxygen sensor

② white tip: it is caused by silicon pollution. At this time, the oxygen sensor must be replaced

③ Brown Tip: it is caused by lead pollution. If it is serious, the oxygen sensor must also be replaced

its TG is 60 ~ 65 ℃ ④black tip: it is caused by carbon deposition. Generally, the carbon deposition on the oxygen sensor can be removed automatically after the carbon deposition fault of the engine is eliminated. Imported pump valve industrial washing machine

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