1995 Mercedes Benz S320 P0411 Fault: How to Diagnose and Fix Secondary Air Injection System Issues

Model: 1995 Mercedes Benz S320 Fault Code: P0411 Posted: 2014-03-25 14:55

I own a 1995 Mercedes-Benz S320 with fault code P0411, which indicates an issue with the secondary air injection system. I understand this relates to the air injection pump, but I need a step-by-step diagnostic flowchart to troubleshoot it effectively. I've already tested the air injection pump and confirmed it works when powered directly with 12V. All vacuum hoses have been replaced and inspected for leaks. However, I'm still unsure about the location of the relay that controls the system, if there's a dedicated computer module managing the air injection pump (AIP), and where exactly this control unit is located. Additionally, I'm uncertain whether the valve situated at the front of the engine is functioning properly. Could someone provide guidance on how to test or repair this component? Any detailed troubleshooting steps would be greatly appreciated.