First, ignore the dirt on the leading edge of the air filter pleats. All air filters accumulate dirt on the leading edges in as little as a few thousand miles. Yet most last for about 12,000 miles. You want to know how much dirt has penetrated deep into the pleats. To test the true condition of your filter, hold a shop light behind it. See how much light passes through the inner pleats and compare yours with the three sample photos (after Photo 2). The filter labeled “replace” is totally clogged and costs the owner a fortune in wasted gas. The filter labeled “borderline” shows a clogged area, but the rest of the filter has decent light transmission. It’s borderline, and the owner could probably squeeze 2,000 to 3,000 more miles out of it. It should be replaced at the next oil change interval. The last filter shows how much light passes through a new filter.
1: Remove the filter
Follow the black plastic duct to the air filter box. Unscrew or unsnap the latches. Remove the filter. Note that the screen always faces the engine. The pleats face the incoming air.
2: Inspect the filter
Hold the filter over a shop light and compare it with the three air filters in the next photo. Reinstall or replace.
Air filter wear
The amount of light coming through the filter indicates whether it needs to be replaced.