Diagnostic Overview
CAT fault code SPN4110 is best normalized as SPN 411 FMI 0 when entered as a combined code. SPN 411 commonly relates to EGR differential pressure or EGR flow measurement. FMI 0 indicates the value is above normal at a high-severity level. In practical terms, the ECM may believe EGR flow or pressure is too high. The cause may be a true EGR flow problem or a sensor/tube issue creating an incorrect reading.
Likely Causes
Plugged or restricted EGR differential pressure tubes; faulty EGR pressure sensor; stuck-open EGR valve; carbon buildup; exhaust restriction; wiring issue; sensor port contamination.
What To Check First
Inspect and clean EGR pressure tubes and ports, compare live EGR pressure data, test EGR valve movement, and check for related intake or exhaust restrictions.