Diagnostic Overview
Volvo fault code SPN 411 FMI 2 is commonly treated as an EGR differential pressure or EGR flow signal fault. The ECM uses EGR pressure feedback to determine whether commanded EGR flow is actually occurring. A wrong signal can lead to incorrect EGR control, increased soot, poor turbo response, or repeated aftertreatment problems.
Likely Causes
Plugged EGR differential pressure tubes; failed pressure sensor; damaged sensor wiring; loose connector; carbon blockage; EGR cooler restriction; exhaust leak.
What To Check First
Inspect and clean EGR pressure tubes, verify pressure sensor voltage/live data, check connector pins, and test EGR flow during commanded operation.