1. Symptoms of oxygen sensor failure
If the oxygen sensor fails, the idle speed will be unstable and the consumption will be excessive. A damaged oxygen sensor obviously results in insufficient engine power, slow acceleration, and black smoke from the exhaust. If the oxygen sensor fails, the engine fault light will usually light up, the engine will idle unstable, the exhaust will make a popping sound, and there will be a pungent smell, and the fuel consumption will increase. You can use a fault diagnosis tool to check the voltage, which is usually between 0.1-1 volts. Change, the number of changes exceeds 8 times in 10 seconds. If the voltage changes between 0.1-0.5 volts, it means the mixture is too lean. If it changes between 0.5-1 volts, it means the mixture is too rich. If it changes between 0.4-0.5 If it doesn’t move, the oxygen sensor is damaged.
2. How to check the quality of the oxygen sensor
The inspection of oxygen sensor performance is divided into three situations. One is to detect the sensor resistance; the second is to measure the change in the voltage output signal of the oxygen sensor; the third is to observe the color of the appearance of the oxygen sensor.
1. Check the resistance of the oxygen sensor
When the engine temperature reaches normal, unplug the wire connector of the oxygen sensor and use a resistance meter to check the resistance of the pressure sensor. The resistance value between the terminals should meet the standard value requirements of the specific vehicle model (generally 440Ω). If the resistance value does not meet the requirements, the oxygen sensor should be replaced.
2. Check the oxygen sensor voltage
The oxygen sensor voltage output signal is detected by installing the oxygen sensor wire connector from the signal terminal. Lead out a wire, start the engine, allow the engine to reach normal operating temperature, and maintain the engine at idle speed. At this time, use a voltmeter to detect the output voltage of the oxygen sensor signal terminal. When the high-voltage distribution line of a cylinder is unplugged (fire failure), the oxygen content in the exhaust gas will decrease. If the voltage indicated by the voltmeter increases, it means that the sensor performance is good (the output voltage of the oxygen sensor is generally 0.20.9V between, its variation range is around 0.5V).
3. Observe the color of the appearance of the oxygen sensor
When inspecting the oxygen sensor, sometimes the cause of the fault can also be known by observing the color of the top of the oxygen sensor. . The normal color of the oxygen sensor tip is light gray. Once the color of the oxygen sensor tip changes, it indicates that there is a fault or hidden danger of the oxygen sensor.
①Light gray top: This is the normal color of the oxygen sensor.color.
②White tip: caused by silicon pollution, the oxygen sensor must be replaced at this time.
③Brown tip: caused by lead contamination. If serious, the oxygen sensor must be replaced.
④Black top: It is caused by carbon deposits. After the engine carbon deposit fault is eliminated, the carbon deposits on the oxygen sensor can generally be automatically removed.
3. What are the common faults of oxygen sensors?
1. Oxygen sensor poisoning
Oxygen sensor Poisoning is a common fault that is difficult to prevent and cure, especially in cars that often use leaded gasoline. Even a new oxygen sensor can only work for a few thousand kilometers. If there is only mild lead poisoning, then using a tank of unleaded gasoline can eliminate the lead on the surface of the oxygen sensor and return it to normal operation. However, often due to excessive exhaust temperature, lead invades its interior, hindering the diffusion of oxygen ions and causing the oxygen sensor to fail. At this time, it can only be replaced.
In addition, silicon poisoning of oxygen sensors is also common. Generally speaking, the silica generated after the combustion of silicon compounds contained in gasoline and lubricating oil, and the organic silicon gas emitted by improper use of silicone rubber sealing gaskets will cause the oxygen sensor to fail. Therefore, good quality fuel and lubricating oil must be used. . When repairing, be sure to correctly select and install the rubber gasket, and do not apply solvents and anti-adhesive agents other than those specified by the manufacturer on the sensor.
2. Carbon deposits on the surface of the oxygen sensor
Due to poor engine combustion, carbon deposits form on the surface of the oxygen sensor, or oil or dust enters the interior of the oxygen sensor. Such sediments will hinder or block the outside air from entering the inside of the oxygen sensor, causing the signal output by the oxygen sensor to be inaccurate, and the ECU cannot correct the air-fuel ratio in a timely manner. The main manifestations of carbon deposits are increased fuel consumption and a significant increase in emission concentration. At this time, if the sediment is removed, normal operation will resume.
3. The ceramic of the oxygen sensor is broken
The ceramic of the oxygen sensor is hard and brittle. It may be damaged by hitting it with a hard object or blowing it with a strong air flow. Cause it to break into pieces and become ineffective. Therefore, be particularly careful when handling and replace them promptly if problems are found.
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