To Rick,... It is too bad they did not change your battery air filter, but this is not a major issue. However this is a part very specific to this vehicle, it is not a part ANY dealer is expected to keep in stock. However, if you schedule your car for service at least 3 days in advance, any dealer should have the part within 3 days from a Ford distribution center.

Salsbr, It is hard for me to belive you got a check engine light for the battery air filter. In fact, I think this is impossible. If you got a check engine light, something else was wrong, and this was a coincidence.

This air filter is not a mission critical part. You could probably drive 100,000 miles without a filter and be fine, or drive 100,000 miles with a dirty filter and be fine, just neither case is ideal.

A friend I know who lives in the Calif desert on dirt roads gets his filter "dirty" in 5000 miles or less. He washes it with water, lets it dry, and puts it back in. It has been fine for 2.5 years this way.

So "replacing" this filter may be the option for people short on time.
Washing and replacing the same filter may be the best option for people short on money, and have 5 minutes to spare.
-John