Which of the following indicates the air filter needs service?

• A. Engine overheating.
• B. Excessive smoke out of exhaust.
• C. Bar not turning.
• D. Noticeable power loss and visible dirt or reduced air flow in the intake.

Answer: (D)

Airflow is essential for engine performance. When the air filter is dirty or clogged, it restricts air from entering the engine, causing a lean fuel-air mixture and reduced power. In a chainsaw, you’re more likely to notice signs directly tied to the intake, such as visible dirt in the intake path or a clear drop in engine power. That combination—power loss plus dirt or reduced airflow in the intake—is the strongest indication that the air filter needs service: it points to restricted breathing for the engine.

Other symptoms like overheating, excess exhaust smoke, or the bar not turning come from different systems—cooling, fuel/exhaust issues, or drivetrain/clutch problems—and don’t specifically signal that the air filter needs service.