Loading ...Q My check engine light is on (97 328i) and I scanned it with the BavAuto tool. Codes are F6 and F5, which I believe are secondary air system flow too low cyl #1-3 and cyl # 4-6. How can I fix the problem?
A With the “Secondary air system flow too low” fault codes, you likely need to replace the secondary air pump and the check valve at the exhaust manifold. The common failure is for the check valve to stick open which allows exhaust gas to enter the pump when it is not running. This eventually destroys the pump. Therefore, the common repair is to replace both the pump and the check valve.
There is some testing that you can do in order to verify if the pump or the check valve (or both) are faulty. See the Summer 2008 issue of our Fast Times newsletter for a DIY on diagnosing the Secondary Air System.
Click here for the Bavarian Autosport Summer 2008 Fast Times nesletter:
http://www.bavauto.com/newsletter/2008_n408_newsletter.pdf
Click here for Secondary Air System pumps, check valves and accessories:
http://www.bavauto.com/se1.asp?dept_id=346
