What does Cummins fault code SPN 105 FMI 3 mean?

Q: What does Cummins fault code SPN 105 FMI 3 mean?

SPN 105 FMI 3 indicates: High idle; Excessive black smoke; Fan stays on 100% of the time. Fix: Intake Manifold Temp High (Voltage). LOGIC: Signal > 4.5V (Open Circuit). When the wire breaks, the ECM thinks it is -40°F (or max cold), so it over-fuels and runs the fan. ACTION: 1. Locate sensor on intake horn. 2. Jumper pins to check for FMI 4 transition. 3. Check for soot/oil buildup on the thermistor tip. FIX: Replace Intake Air Temp Sensor or repair wire break at the connector.

Cummins Fault Code

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SPN 105 FMI 3

High idle; Excessive black smoke; Fan stays on 100% of the time.

System

Not specified

Symptom

High idle; Excessive black smoke; Fan stays on 100% of the time.

Diagnosis & fix steps

Intake Manifold Temp High (Voltage). LOGIC: Signal > 4.5V (Open Circuit). When the wire breaks, the ECM thinks it is -40°F (or max cold), so it over-fuels and runs the fan. ACTION: 1. Locate sensor on intake horn. 2. Jumper pins to check for FMI 4 transition. 3. Check for soot/oil buildup on the thermistor tip. FIX: Replace Intake Air Temp Sensor or repair wire break at the connector.

Red Seal field insights

If the fan is screaming and won't turn off, check this code first. The ECM runs the fan as a safety measure when it loses the intake temp signal.

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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