The common signs of a dirty air filter mainly include changes in appearance, decreased engine performance, and abnormal emissions. Regarding engine performance, insufficient air intake results in sluggish acceleration and diminished power output. A muffled sound or difficulty in RPM increase may be observed when depressing the accelerator, particularly noticeable during hill climbing or full-load conditions. In the emission system, incomplete combustion leads to darkened exhaust gas (manifesting as black smoke) accompanied by a pungent petrol odor or burning smell. Certain vehicle models may illuminate an air flow warning indicator on the dashboard or register abnormal intake data through the diagnostic system. Furthermore, prolonged use of a contaminated filter accelerates carbon deposit formation and elevates fuel consumption (potentially increasing by 10%-15%). In extreme scenarios, it may induce idle roughness or even engine stall during operation. Regular inspection of the filter condition is advised every 10,000 to 15,000 kilometres, with replacement intervals reduced to under 10,000 kilometres in harsh environmental conditions to maintain optimal engine efficiency and prolong service life.
