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SPN 111 FMI 4

SPN 111 FMI 4: Engine coolant level circuit voltage low – shorted low

Quick Answer

When SPN 111 FMI 4 sets, the ECM is indicating a fault condition involving the component or system named in the code.

OEM definitions and thresholds can vary, so confirm the exact meaning with service information or a capable diagnostic tool.

Code
SPN 111 FMI 4
Severity
Info
Applies to
Check OEM application
Can I drive?
The immediate driving effect of SPN 111 FMI 4 depends on whether the fault is active, the component involved, and any companion codes. If it repeats after clearing, diagnose it as an active fault rather than continuing to reset it.

Common Symptoms

  • Check-engine light or coolant-level circuit fault
  • Coolant level reading may be unavailable or unreliable

Likely Causes

  • Coolant level sensor circuit shorted to ground
  • Damaged or corroded coolant level sensor wiring
  • Coolant level sensor or connector fault

Quick Diagnostic Checks

Check first
  1. 1Scan for companion codes and record freeze-frame data (if available).
  2. 2Inspect connectors, harness rub points, and pins for corrosion.
  3. 3Check for other active faults that may be upstream causes (communications, sensors, air/fuel issues).
  4. 4After repair, clear codes and confirm the fault stays inactive after a drive cycle.

Common Fixes

  • Inspect the coolant level sensor connector and harness
  • Test the circuit for a short to ground using the OEM wiring diagram
  • Repair the circuit or replace the sensor only after testing identifies the fault
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FitmentsMeaningHow it worksImagesDetailed guideOEM/Engine notesLocation hintScan tool checksStep-by-step diagnosticDecision guideMisdiagnosisDerate/inducementChecklistToolsPreventionCommunity discussionsCommunity videosCommunity notesShare

What does SPN 111 FMI 4 mean?

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When SPN 111 FMI 4 sets, the ECM is indicating a fault condition involving the component or system named in the code.

OEM definitions and thresholds can vary, so confirm the exact meaning with service information or a capable diagnostic tool.

Treat repeat faults as ACTIVE and diagnose using live data, wiring checks, and basic inspections before replacing parts.

How this system works (why SPN 111 FMI 4 happens)

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Most modern fault logic is based on expected versus actual sensor readings, timing windows, circuit checks, and plausibility tests.

A stored code can come from a temporary event, while a repeatable active code gives you a much better diagnostic target.

The goal is to identify whether the failure is electrical, mechanical, sensor-related, or caused by another upstream fault before replacing components.

Detailed guide for SPN 111 FMI 4

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What SPN 111 FMI 4 means

SPN 111 identifies engine coolant level. FMI 4 indicates voltage below normal or a circuit shorted toward a low source.

Detroit documentation describes this fault as a coolant level circuit failed low condition and directs diagnosis toward the sensor circuit and possible short to ground.

What to check first

Inspect the coolant level sensor connector for bent, spread or corroded terminals. Examine the harness near the radiator, reservoir and chassis for chafing or damaged insulation.

Use the manufacturer's wiring diagram to test the coolant level circuit for a short to ground and verify circuit integrity.

Also confirm the actual coolant level because some applications can associate the circuit condition with a low-level state.

Before replacing the sensor

Do not replace the sensor without circuit testing. Wiring faults can produce the same FMI.

After repairs, clear the fault according to the OEM procedure and verify that the coolant-level signal is operating normally.

Location hint for SPN 111 FMI 4

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Component location varies by OEM and chassis. Use your engine’s service manual to confirm the sensor/valve location before replacing parts.

Tip: Inspect connectors and harness routing before replacing parts.

Scan tool checks for SPN 111 FMI 4

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  • Check status: ACTIVE vs INACTIVE / stored and review freeze-frame data when available.
  • Record companion codes and diagnose the earliest or most upstream fault first.
  • Compare live sensor values with expected operating conditions and inspect wiring and connectors.
  • Clear and re-test under similar conditions only after completing the initial inspection.

If your tool can’t run actuator tests, you can still diagnose a lot with careful inspection + repeatability testing.

Step-by-step diagnostic for SPN 111 FMI 4

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  1. Visual inspection (fast wins). Harness routing, connector pins, hoses/lines (if applicable), and obvious damage.
  2. Check fluid sanity. Not applicable unless your fault is fluid-related. Focus on inspections + repeatability.
  3. Confirm the fault is ACTIVE. Stored-only faults can be old events.
  4. Review live data and circuit values. Use OEM diagnostic software (examples: Cummins INSITE, Detroit DDDL, PACCAR DAVIE4) or a capable heavy-duty scan tool to review the affected signal, commanded/actual values when applicable, and related sensor data.
  5. Verify after repair. Clear codes, road test, confirm it stays inactive.

Decision guide (fast path) for SPN 111 FMI 4

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  • If the fault is STORED only → inspect, clear, and monitor. If it returns, treat it as active.
  • If ACTIVE → inspect the named component, connector, harness, supply/ground, and live-data plausibility.
  • If multiple codes are present → diagnose the earliest or most upstream code first.

Common misdiagnosis mistakes for SPN 111 FMI 4

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  • Replacing sensors or components without checking wiring, grounds, connector fitment, and companion codes.
  • Clearing the fault repeatedly without confirming whether it is ACTIVE and repeatable.
  • Missing an upstream fault that is causing the displayed code as a secondary symptom.

Will SPN 111 FMI 4 cause derate or inducement?

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This fault may not require immediate shutdown, but repeated or active faults should still be diagnosed.

Exact behavior depends on ECM calibration and which companion faults are active.

“Do this first” checklist for SPN 111 FMI 4

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  • Scan for companion codes and record freeze-frame data (if available).
  • Inspect connectors, harness rub points, and pins for corrosion.
  • Check for other active faults that may be upstream causes (communications, sensors, air/fuel issues).
  • After repair, clear codes and confirm the fault stays inactive after a drive cycle.

Tools needed to diagnose SPN 111 FMI 4

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  • Basic hand tools + good lighting for inspection
  • Multimeter for connector/power/ground checks (if wiring suspected)
  • OEM diagnostic software (examples: Cummins INSITE, Detroit DDDL, PACCAR DAVIE4) (or equivalent scan tool) for live data and supported diagnostic tests

Prevention tips to avoid repeat SPN 111 FMI 4

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  • Fix small wiring/connector issues early before they become repeat faults.
  • During service, inspect harness routing and clamp points near heat/vibration.
  • Don’t ignore intermittent faults. “Erratic” usually gets worse.

Video walkthrough for SPN 111 FMI 4

The videos below are embedded using YouTube’s official player. We do not host or claim ownership of this content. Use it as a visual reference and always confirm with diagnostics for your exact truck configuration.

SPN 111 FMI 4 Detroit DD13 Freightliner
Channel: Mecaniconsejos JN • View in BigRigFaults Media • YouTube source
If a creator disables embedding, the video will stop showing here. That’s normal and it’s their right.
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Mechanic community notes for SPN 111 FMI 4

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