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Old 09-09-2010, 09:11 PM   #8
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Join Date: Nov 2006
Location: Edmonton, Canada
Posts: 2,226
My Ride: 2003 325xi
Originally Posted by ruckus323 View Post
Great thread! I was just taking pictures of this hose to ask what it was. Mine is completely deteriorated and succumbed to awesome power of one finger press.

What is the failure mode of a SAP or the hose leaking?? What is the function of the part?
The SAP pumps extra oxygen to the unburned fuel in the exhaust, so that hydrocarbons oxidize and carbon monoxide combines with oxygen to form carbon dioxide and water. Leaks or blockage gives the "low secondary air flow" CEL.
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