Which step is essential when inspecting the air filter?

When inspecting the air filter, wiping away dirt and debris is essential because the air filter's primary function is to prevent contaminants, such as dirt, dust, and debris, from entering the engine. A clean air filter allows for proper airflow, which is crucial for engine performance and efficiency. If the air filter is dirty or clogged, it can restrict airflow, leading to poor engine performance, reduced fuel efficiency, and potential engine damage over time. Regular inspection and cleaning of the air filter can significantly impact the engine's overall health and reliability, ensuring it runs smoothly and efficiently.

In this context, adjusting the throttle, cleaning fuel injectors, and changing the oil do not directly relate to the maintenance of the air filter. Each of these actions serves a different purpose in engine maintenance, but they do not address the condition or cleanliness of the air filter itself.