← Back to Detroit Diesel Fault Codes
Detroit Diesel SPN 1569 FMI 31 indicates an engine protection derate condition. The ECM has limited engine power to protect critical components due to an active fault.
Symptoms
- Reduced engine power
- Limited vehicle speed
- Check engine light illuminated
- Possible shutdown warning
Cause
SPN 1569 FMI 31 is typically triggered when a critical engine fault has occurred. This may include high coolant temperature, low oil pressure, aftertreatment system issues, or DEF system faults.
Can You Keep Driving?
Driving may be possible at reduced power, but continued operation without diagnosing the underlying fault may lead to further engine damage.
Recommended Action
Diagnose underlying active fault codes using a diagnostic tool. Repair the primary issue before clearing the derate condition.
Need Immediate Help With This Fault Code?
If your engine is derating, losing power, or unable to complete regeneration, don’t risk further damage or costly downtime.
Use 4RoadService to locate mobile truck repair, dealer diagnostics, or emergency roadside assistance near your location.
Important Notice
The information provided above is for general informational purposes only and should not replace official OEM service procedures. Always consult the manufacturer’s service manual or a qualified diesel technician before performing repairs. Operating a vehicle with active fault codes may result in further damage.