The alarm of the diesel fine filter may be caused by water ingress. The reasons and solutions are as follows: 

1. The filter element of the diesel filter is mostly filter paper, and some are made of felt or polymer materials. Diesel filter can be divided into diesel water separator and diesel fine filter. The important function of the oil-water separator is to separate the water in the diesel. The presence of water is extremely harmful to the diesel engine fuel supply system, rust, wear, and seizure can even worsen the combustion process of diesel. Due to the high sulfur content in Chinese diesel, when combustion occurs, it will even react with water to form sulfuric acid to corrode engine parts. The traditional way of removing water is mainly precipitation, through the funnel structure. Engines with emissions from National III and above have higher requirements for water separation, and the higher requirements require the use of high-performance filter media;
2. Reason: There is only one possibility for the diesel filter element to enter water. The outside enters, and it is impossible to produce water out of thin air in the fuel tank. So either it is the quality of the diesel, or moisture can enter somewhere in the fuel tank. If there is a lot of water in the diesel filter element, focus on checking whether the lower fuel tank cap is sealed and whether there are leaks in the upper part of the fuel tank, etc.;
3. Solution: Turn off the fuel tank switch, and then turn it on after removing the fuel pipe. Make the water flow in the container, turn off the switch when the diesel oil flows out, and install the oil pipe. The effluent in the container is precipitated, and after the oil and water are separated, the upper diesel oil is poured back into the fuel tank. Remove the screw plug under the filter to allow the diesel to flow into the container. Tighten the screw plug after the diesel oil flows out. Treat the effluent in the container as described above.