Cummins Fault Code
Free · no signup151 (SPN 110 FMI 0)
Progressive engine derate; Shutdown protection active; Fan at 100%.
System
Not specified
Symptom
Progressive engine derate; Shutdown protection active; Fan at 100%.
Diagnosis & fix steps
Coolant Temperature High - Critical.
LOGIC: Temperature has exceeded the "Most Severe" limit.
ACTION: 1. Verify actual temp with an IR gun at the thermostat housing.
2. Check radiator for "winter front" or mud blockage.
3. Check for aerated coolant (combustion leak).
FIX: Clean radiator/CAC; replace Thermostat; replace Water Pump.
Red Seal field insights
Critical: If the IR gun shows the engine is cool but 151 is active, the sensor is "drifting." However, if 151 is active, treat it as a real overheat until proven otherwise to avoid a cracked head.
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