Cummins ISX15 / X15 SPN 1569 FMI 31 �?Engine Protection Torque Derate Active

Code Details

Plain-English Meaning

The Cummins engine protection system monitors critical parameters and reduces engine power when any value crosses a threshold that risks engine or aftertreatment damage. SPN 1569 FMI 31 confirms a derate is occurring, but the underlying cause is found in the companion fault codes that triggered the protection event.

SPN 1569 is the Engine Protection Torque Derate parameter in J1939. FMI 31 indicates a condition exists confirming active derate via the protection strategy. On Cummins CM2350, the derate magnitude depends on which protective limit was crossed and how far the parameter deviates from normal. Common triggers include high coolant temperature, low oil pressure, SCR or aftertreatment inducement reaching the derate stage, high exhaust temperature, or multiple co-occurring faults that collectively activate the protection logic.

Common Symptoms

• Noticeable reduction in engine power or available torque
• Vehicle may be limited to a maximum speed
• Check engine or engine protection lamp active
• Multiple other fault codes active simultaneously
• Driver display showing a derate or engine protection message

Possible Causes

Possible causes may include the items below. The list is not a parts diagnosis.

• SCR or aftertreatment inducement has reached the derate stage due to DEF or catalyst issues
• High coolant temperature from a cooling system fault
• Low engine oil pressure from low oil level, worn oil pump, or restricted oil passages
• High exhaust temperature or DPF overload condition
• Multiple simultaneous fault codes that collectively trigger the protection strategy

First Checks

• Connect Cummins Insite immediately and review all active fault codes to identify the primary trigger for the protection derate
• Check coolant level and temperature, engine oil level and pressure, and DEF level as quick baseline checks
• Address the root cause indicated by companion codes �?SPN 1569 FMI 31 will clear when the triggering parameter returns to normal
• Do not clear SPN 1569 without resolving the underlying cause �?the derate returns immediately if the root condition persists
• If SCR-related, check the inducement counter in Insite to understand how deep into the derate sequence the system has progressed

Can I Keep Driving?

The truck is actively derated while SPN 1569 FMI 31 is present. Power and possibly vehicle speed are limited. Continued operation with the triggering condition unresolved risks escalation to a full shutdown in severe cases.

Related Lookup Pages

• SPN 1569 topic page
• FMI 31 explanation
• Cummins manufacturer hub
• Search this code