Diesel engines are key constituents in numerous sectors and play a pivotal function in various system configurations. Their combination of high power generation and efficiency renders them highly sought after. Although these engines hold great importance, they are susceptible to numerous issues arising from environmental conditions. Diesel engine air filter contamination is one of the most common types of problems. This pollution has the potential to cause significant issues by impacting the combustion processes of diesel engines. In this line, this study investigated how air filter pollution impacts combustion, fuel consumption, and emissions using a full-mission engine room simulator. A turbocharged, low-speed, two-stroke marine diesel engine was utilized in the simulation, with engine characteristics being monitored as air filter contamination was gradually applied to the simulation. It was found that air filter contamination has a detrimental impact on the combustion process in diesel engines, resulting in decreased compression and combustion pressures within the cylinders. Furthermore, the simulation resulted in increased levels of CO and SOx, while causing a decrease in NOx emissions. Ultimately, the presence of air filter pollution resulted in an increase in fuel consumption for diesel engines. The findings will highlight the importance of filter maintenance in diesel engines and support the use of modern maintenance practices derived from innovative methodologies.