An annual output of the Volkswagen Skoda Octavia 1.6L sedan, the user reflects the car dashboard on the fuel gauge pointer sometimes automatically return to zero.
    After receiving the car, the maintenance personnel connected to the fault diagnosis instrument to detect the vehicle, fault diagnosis instrument prompted fuel oil level sensor mechanical failure. To this end, the maintenance staff using the diagnostic diagnostic function of the diagnostic device on the fuel table was driven, the results of the needle from zero to full grid, and then can return to the 1/2 position, everything is normal. After that, the maintenance personnel decided to remove the fuel level sensor to check. When the maintenance personnel disconnect the fuel pump plug, found that the fuel pump harness plug is very wet. After careful observation, the liquid is like water, smell with the nose and no smell of gasoline, the initial determination of the fault is caused by the wiring harness seal lax caused by leakage. In view of the previous encounter such a failure, so the maintenance staff for the car to replace the wiring harness and handle the socket, then the car delivery.
    But this car in about 1 month after the failure to reproduce. As the fault has been repaired twice, the user expressed a certain degree of dissatisfaction. First, the maintenance personnel with the fault diagnosis instrument VAS5051 on the vehicle to detect, the device shows the same with the previous two fault code. As a result of the previous experience, the maintenance personnel directly open the pump plug to check and find the plug or wet. Oil pump plug just changed, should not plug the seal caused by leakage, then where is the water from? We suspect that the liquid is gasoline. Although there is no smell of gasoline, will it be a long time volatile it? Generally leaking gasoline will have a lot of gasoline flavor. In order to determine whether it is gasoline, we use toilet paper to wipe a bit, and then lit with a lighter and found that toilet paper is difficult to be ignited. After the maintenance personnel and the use of engine exhaust gas analyzer for detection, did not find HC components, it can be determined that the liquid is not gasoline.
    Maintenance personnel carefully consult the user that the car has not been involved in water recently, and this time we open the fuel pump on the cover and found that there is a layer of ash on the fuel pump, there is no traces of water. At this point the repair has been difficult, the fuel pump plug is wet, but not into the water and not gasoline. Maintenance personnel suspected that the maintenance staff in the last maintenance did not line the water treatment clean, so we decided to open the plug completely clean up. After thoroughly cleaning the liquid inside the line, we have replaced the fuel pump of the car and advise the user to continue to use it.
    The user will drive away a week later, the car will be due to the same failure back to the factory. After receiving the car, connect the fault diagnosis device to detect the vehicle, the device still shows the previous fault code. Then the maintenance staff disconnected the fuel pump plug, after careful observation found that the liquid in the socket was significantly more than the previous two times. In view of the previous experience, you can determine the liquid is not gasoline, then it will not be antifreeze? In view of the antifreeze are color, maintenance personnel decided to use the light to observe whether it is colored liquid, but look carefully For a long time can not see the color. At this point the maintenance staff suddenly think of antifreeze is a freezing point, so we can use the freezing point tester to measure its freezing point to determine whether it is antifreeze. The freezing point tester, the liquid really has a freezing point of about -20 ° C, so it can be determined that the liquid is antifreeze.
    Where is the antifreeze, then where do they come from? Between the wiring harness and the antifreeze, the engine coolant temperature sensor is connected to the engine harness and the coolant level sensor is connected to the instrument-related harness, so it should focus on these two The sensor is checked. Maintenance personnel to open the engine hatch, the inspection found that the coolant temperature sensor harness plug normal, but in the coolant level sensor plug found a lot of antifreeze. Then open the combination of instruments found that the combination of instrument plug a lot of scale. The cause of the failure is finally found, due to the coolant level sensor leakage, resulting in antifreeze along the wiring harness to reach the combination of instrument plug, and further along the big line to reach the fuel pump plug, resulting in fuel oil level sensor pin signal abnormalities, Resulting in the fuel gauge pointer on the dashboard sometimes placed in the zero position. In the replacement of antifreeze expansion tank and the whole line after the wiring harness, troubleshooting.