Cummins Fault Code

Free · no signup

Cummins 144 (SPN 110 FMI 4)

Fan stays on 100%; Gauge pinned to Hot; Hard starting in cold weather; Engine derate.

System

Not specified

Symptom

Fan stays on 100%; Gauge pinned to Hot; Hard starting in cold weather; Engine derate.

Diagnosis & fix steps

Engine Coolant Temperature 1 Sensor Circuit - Voltage Low. LOGIC: Signal voltage < 0.5V (Short to Ground). The ECM interprets a dead short as an extremely high temperature or a circuit failure. ACTION: 1. The "Unplug" Test: Unplug the sensor. If the code changes to 145 (FMI 3 - Voltage High), the wiring is healthy and the Sensor is shorted internally. 2. Harness Inspection: Check for rub-points on the harness near the thermostat housing or lifting brackets. 3. Reference Check: Verify 5.0V between Pin A and Pin B on the harness plug with the key ON. FIX: Replace the Engine Coolant Temperature Sensor or repair the signal wire shorted to ground.

Red Seal field insights

This sensor is often located near the thermostat housing. If you've recently done a coolant flush or water pump, check the connector for trapped moisture or "Green Crusties" which can track voltage to ground.

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.

Book an uptime review

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.

Track this across your whole fleet

This code is free to read. AM Fleet Integrity lets your team log fault codes against assets, plus the full fault-code library, QR operator reporting, PM scheduling and predictive alerts. Start free — no credit card required.

Start your free trial

Related Cummins fault codes

← All Cummins fault codes