What does Cummins fault code 151 (SPN 110 FMI 0) mean?

Q: What does Cummins fault code 151 (SPN 110 FMI 0) mean?

151 (SPN 110 FMI 0) indicates: Progressive engine derate; Shutdown protection active; Fan at 100%. Fix: 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.

Cummins Fault Code

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151 (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.

Same code keeps coming back?

That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.

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Read before you touch anything

This is general reference information, not a repair manual. It is for trained, qualified technicians.
Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.

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