Truck Fault Codes

PACCAR MX-13 SPN 1569 FMI 31 �?Engine Protection Torque Derate Active

SPN 1569 FMI 31 on a PACCAR MX-13 means the engine protection system is actively derating torque. This is a secondary indicator �?check companion active codes to identify the trigger: coolant temperature, oil pressure, SCR inducement, or DPF soot loading.

Code Details

Structured details for SPN 1569 FMI 31
Display codeSPN 1569 FMI 31
SPN1569
FMI31
OEM codeNone listed
ManufacturerPACCAR
SystemEngine protection / aftertreatment
ComponentEngine control unit �?protection strategy
Source addressUnknown or not applicable
Severityhigh
Review statussource backed
Source confidencemedium
Last reviewed2026-06-11

Plain-English Meaning

The PACCAR MX-13 ECU monitors critical engine and aftertreatment parameters and reduces power when any value crosses a protective threshold. SPN 1569 FMI 31 confirms a derate is active, but the companion fault codes identify why. The root cause must be resolved for the derate to clear. On Kenworth T680, T880, and Peterbilt 579 trucks with the MX-13, the SCR inducement counter in DAVIE4 shows the remaining distance until maximum derate. The repair sequence is the same as all other J1939 platforms: identify root cause faults, repair them, confirm aftertreatment system function, and then reset the inducement counter via DAVIE4. PACCAR dealers use a specific DAVIE4 procedure for the inducement reset that confirms all active aftertreatment faults are resolved before allowing the counter to clear.

SPN 1569 is the Engine Protection Torque Derate parameter in J1939. FMI 31 indicates the derate is currently active on the PACCAR MX-13 control system. Common triggers include SCR inducement reaching the derate stage, high coolant temperature, low oil pressure, and critical DPF soot loading. The derate magnitude scales with the severity of the triggering condition.

Common Symptoms

  • Noticeable reduction in available power
  • Possible vehicle speed limitation
  • Check engine or engine protection warning active
  • Multiple companion fault codes visible in PACCAR diagnostic software

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 pump issues
  • DPF soot overload at the critical threshold
  • Multiple simultaneous faults triggering the protection strategy

First Checks

  • Connect PACCAR DAVIE and review all active fault codes to identify the primary protection trigger
  • Check coolant level and temperature, oil level, and DEF quality as quick baseline checks
  • Resolve the underlying cause �?SPN 1569 FMI 31 will clear when the triggering parameter normalizes
  • Do not clear the fault without addressing the root cause
  • Connect DAVIE4 and identify all active fault codes contributing to the SPN 1569 inducement
  • After all root cause repairs, use DAVIE4 inducement reset procedure to restore full engine power

Can I Keep Driving?

The MX-13 is actively derated with reduced power. If the trigger is a cooling or lubrication issue, continued operation risks engine damage. If aftertreatment-related, the derate deepens with additional distance. Prioritize diagnosis and repair.

SPN 5246 FMI 31Aftertreatment �?SCR system · SCR catalyst / NOx sensorsSPN 3251 FMI 0Aftertreatment �?DPF system · Diesel particulate filter / differential pressure sensor

Related Lookup Pages

Sources

  • PACCAR / Kenworth / Peterbilt Service Support — MX Engine Resources PACCAR Inc. · oem · accessed 2026-06-11 · confidence medium

    Source: PACCAR Inc., PACCAR / Kenworth / Peterbilt Service Support — MX Engine Resources. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source
  • PACCAR Engine Technical Services PACCAR Inc. · oem · accessed 2026-06-10 · confidence medium

    Source: PACCAR Inc., PACCAR Engine Technical Services. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source
  • SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium

    Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.

    Open source

FAQ

Can I drive a Kenworth or Peterbilt to the dealer with SPN 1569 FMI 31 active?

Whether it is safe to drive depends on the companion code that triggered the derate. If the cause is a cooling or oil system issue, driving risks engine damage. If the cause is aftertreatment-related and the engine is running smoothly, a short drive to a dealer or repair facility may be acceptable �?but monitor coolant temperature, oil pressure, and engine behavior closely and pull over if conditions worsen.

What is the most common cause of SPN 1569 FMI 31 on the PACCAR MX-13 in long-haul service?

In long-haul highway applications, the most common trigger is aftertreatment inducement reaching the derate stage �?typically from DEF quality issues or SCR efficiency faults. High coolant temperature is less common on well-maintained cooling systems but can occur in summer operation or with a failing thermostat or fan clutch.

How do I know how deep into the derate sequence the PACCAR MX-13 has progressed?

PACCAR DAVIE displays the inducement counter distance, the current derate percentage, and the fault history for protection events. This information tells you exactly where the engine is in the derate sequence and how much margin remains before the next stage activates.