If a vehicle has been run without the proper air filter, which part would most likely be damaged?

Running a vehicle without the proper air filter can lead to contaminants entering the engine, which can cause significant damage over time. The correct part that is most likely to be damaged in this scenario is the piston ring.

The piston rings are crucial for maintaining the seal between the piston and the cylinder wall. They help to maintain compression within the engine’s combustion chamber and also control oil consumption. If dirt and debris bypass the missing or inadequate air filter, they can scratch or wear down the piston rings and cylinder walls. This wear can lead to reduced compression, increased oil consumption, and overall loss of engine performance. Consequently, maintaining a clean and functional air filter is essential to prevent such damage to the piston rings and ensure the engine operates efficiently.

In contrast, while other components like the camshaft, fuel injector, or plug wire might be affected by poor air quality over time, they are not as directly impacted by the introduction of contaminants as the piston rings are.