What is the secondary air flow? the code popped up on the engine diagnostic of my 2003 ford focus.

The secondary air flow engine code came up on a diagnostic check. What is that and how do I fix it??
Asked Jul 10, 2010
The primary air system feeds into the top of the air filter and the secondary into the bottom. There should be a small filter inside the bottom intake that may need cleaning or replacement.

Download this PDF file and look at the drawing:

Answered Jul 11, 2010

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