Cummins Fault Code
Free · no signupSPN 3031 (FMI 2)
Inducement / 5-MPH Derate.
System
Exhaust (SCR)
Symptom
Inducement / 5-MPH Derate.
Diagnosis & fix steps
LOGIC: Data Erratic / Rationality Fault.
ACTION: Compare Tank Temp to Ambient Air Temp after the machine has sat overnight.
Red Seal field insights
RED SEAL FIX: The ECM compares the DEF tank temp to the Engine Coolant and Ambient Air temps. If the DEF tank says it's 50°C but the air is -5°C, it flags FMI 2. The sensor is "lying."
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