Cummins ISB 6.7 SPN 1569 FMI 31 �?Engine Protection Torque Derate Active

Code Details

Plain-English Meaning

When any critical parameter monitored by the ISB 6.7 ECM exceeds a protective limit, the engine reduces power to protect itself. SPN 1569 FMI 31 confirms the derate is occurring. The companion codes tell you why �?whether it's an overheating issue, an oil pressure problem, or an aftertreatment inducement sequence reaching the derate stage. On Ford F-650/F-750, International, and Kenworth Class 5-6 trucks with the Cummins ISB 6.7, the SCR inducement counter is managed by the ECM and displayed in Insite. The ISB 6.7 is used in many Class 5-6 vocational applications where the vehicle operates within a short radius of a single facility, making depot-based DEF quality control the most effective fleet management strategy. Using only certified DEF from sealed containers and maintaining consistent DEF fill schedules prevents the majority of ISB 6.7 inducement events in fleet service.

SPN 1569 is the Engine Protection Torque Derate parameter in J1939. FMI 31 indicates a protective derate is currently active on the Cummins CM2350B platform. The magnitude of the derate scales with how far the triggering parameter has exceeded its limit. On the ISB 6.7 in medium-duty applications, common triggers include aftertreatment inducement reaching the derate stage, high coolant temperature from cooling issues common in city-cycle operation, and low oil pressure from oil consumption or dilution issues.

Common Symptoms

• Noticeable reduction in engine power during operation
• Possible vehicle speed limitation
• Engine protection or check engine lamp illuminated
• Multiple companion fault codes active in Insite

Possible Causes

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

• SCR or aftertreatment inducement reaching the derate stage
• High coolant temperature from a cooling system fault
• Low engine oil pressure from oil level or oil system issues
• DPF soot overload reaching the critical threshold
• Multiple simultaneous fault codes triggering the protection strategy

First Checks

• Connect Cummins Insite immediately and review all active fault codes to identify the primary protection trigger
• Check coolant level, oil level, and DEF quality as quick baseline checks
• Resolve the underlying cause identified in companion codes �?SPN 1569 FMI 31 will clear when the triggering parameter normalizes
• Do not clear the fault without addressing the root cause
• Connect Insite and review all active aftertreatment fault codes feeding the SPN 1569 inducement
• After root cause repair, use Insite to reset the SCR inducement counter to restore full engine power

Can I Keep Driving?

The vehicle is operating in a derated state with reduced power and possibly speed-limited. Do not ignore this fault in fleet or bus operations �?the underlying condition that triggered the protection derate needs to be identified and resolved before returning the vehicle to service.

Related Lookup Pages

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