Diesel particulate filters (DPFs) are essential tools for controlling pollution emissions. However, some DPFs may encounter failures during operation, thereby posing risks to both the diesel vehicle engine and emission control. Low-quality diesel fuel, due to its higher sulfur content, raises the risk of DPF becoming inactive. This paper examines the reliability of DPFs from a leading national vehicle manufacturer, utilizing after-sales maintenance data. Statistical analysis has been conducted on 10,833 vehicles over the years 2018 to 2022. In addition, the records of failures, the root causes of malfunctions, and the factors influencing the failures of these filters have also been investigated. The results indicate that the highest percentage of failures is associated with urban buses, and the least reliable are mini-buses. In such a way that, it can be stated that the DPFs of all mini-buses malfunction at least once after 17,000 kilometers, which is significantly lower than the defined threshold of 100,000 kilometers. The main causes of damage to the DPF substrate are leaks in the fuel and lubrication systems. Additionally, laboratory analysis of a silicon carbide DPF sample, using scanning electron microscopy (SEM) and X-ray diffraction (XRD), revealed corrosion within the DPF substrate. The chemical compounds obtained from laboratory studies indicate a high percentage of sulfur (2.28% by weight) in diesel fuel and oil leakage into the DPF. Chemical compounds obtained from laboratory studies indicate a high percentage of sulfur (2.28% by weight) in diesel fuel and oil leakage to the DPF. This study accurately demonstrates the alignment of results obtained from simulation, reliability assessment, failure root cause analysis, and laboratory analysis.