Aftertreatment Derate and Inducement: OEM-Specific Stages

Torque reduction and speed restriction vary by engine and calibration; there is no single 55/35/5-mph ladder for every truck.

Record the actual restriction

A derate is a reduction in available performance. Record the displayed lamp, message, torque/speed limitation, timer and companion codes. The observed restriction is evidence; a generic stage name is not an adequate diagnosis.

Separate consequence from cause

SPN 1569 and SPN 5246 can describe limiting conditions. Investigate the complete fault set rather than replacing a component based on the derate code alone. The shared guides identify their application-specific examples.

Use published stages only within scope

Navistar IK0700115 includes a historical Figure 2 progression for its specified applications. It is an example tied to that bulletin, not a current universal schedule. Different thresholds, timers and corrective routines can apply to the truck in front of you. Navistar IK0700115, Figure 2 (2021)

Resolve and verify the underlying condition

• Identify the primary fault and the reliability of the reported data.
• Use the engine-specific diagnostic branch for level, communication, dosing, pressure, NOx or another indicated system.
• Perform the repair supported by the tests.
• Complete any required OEM verification or approved post-repair routine.
• Recheck actual restrictions and the final controller scan.

Ask for help with the full record

Provide engine serial number, model year, controller scan, displayed restrictions and repairs already performed. The post-repair guide explains what must be verified before a reset is treated as successful.

Sources and scope

References describe the applications and editions named in each document. For work on a truck, select current service information by engine serial number, reporting controller and calibration. A general guide does not replace those procedures.

• Navistar IK0700115, Figure 2 (2021)
• Blue Bird SU2103 / Shaw 0000297252, revision B (2021)
• Detroit 01 13-16 (January 2016)