2002 BMW 325i secondary air injection fault?

A secondary air injection fault in a 2002 BMW 325i typically indicates an issue with the secondary air injection system, which helps reduce emissions during cold starts. Common causes include a faulty air pump, clogged air hoses, or issues with the control valves. Diagnostic trouble codes (DTCs) can provide specific error codes to pinpoint the problem. Addressing this issue often involves checking the components for proper operation and replacing any faulty parts.