PACCAR SPN 111 FMI 5: Coolant Level Diagnosis
SPN 111 FMI 5 (FMI 5) — Engine Coolant Level — Current Below Normal or Open Circuit
Quick Answer
On PACCAR, SPN 111 FMI 5 is a Coolant Level fault (Current Below Normal or Open Circuit). Prove wiring/live data first; do not parts-cannon the component.
Overview: PACCAR SPN 111 FMI 5
On PACCAR, SPN 111 FMI 5 is a Coolant Level fault (Current Below Normal or Open Circuit). Prove wiring/live data first; do not parts-cannon the component. This guide covers symptoms, root causes, live-data checks, and misdiagnoses for PACCAR platforms.
Repair Snapshot
Time
1 - 3 Hours
Difficulty
Intermediate
Parts Cost
$50 - $800
Dealer Labor
$350+
Tools Required
- PACCAR Davie
- Noregon JPRO
- Multimeter
What SPN 111 FMI 5 Means
SPN 111 FMI 5 on PACCAR means Engine Coolant Level — Current Below Normal or Open Circuit. Confirm Verify coolant level sensor continuity and tank level with PACCAR Davie / Noregon JPRO before replacing the coolant level.
Symptoms Drivers Notice
- Check-engine / amber warning lamp illuminated.
- Soft power, unstable idle, or poor response when coolant level data is irrational.
- Live data for coolant level fails rationality vs mechanical gauge or partner sensors.
- Codes may return immediately after clearing if root cause remains.
Most Likely Root Causes
Common Misdiagnoses (Don't Waste Parts)
Why it happens:
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Why it happens:
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Why it happens:
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Master Tech Commentary
Mechanic's Notes
Shop tip (PACCAR): For SPN 111 FMI 5, prove Verify coolant level sensor continuity and tank level before quoting the Coolant Level. Common false path is replacing the sensor when the harness or reference circuit is the failure.
Step-by-Step Diagnostic Procedure
- Step 1: Connect PACCAR Davie or Noregon JPRO and record SPN 111 FMI 5 with freeze-frame load/temp.
- Step 2: Inspect harness and connector at the coolant level for chafe, corrosion, and bent pins.
- Step 3: Verify 5V reference / ground / signal integrity with a multimeter where applicable.
- Step 4: Verify coolant level sensor continuity and tank level
- Step 5: Repair the proven fault, clear only after repair, and verify under the same conditions as freeze-frame.
Live Data & Freeze-Frame Tips
Log Coolant Level with PACCAR Davie under freeze-frame conditions. Verify coolant level sensor continuity and tank level. Compare to a mechanical gauge when pressure/temperature related.
When to Limp In vs Tow
Drive carefully to a shop if lamps are warning-only and power remains controllable; tow if power loss is severe.
Related Fault Codes
Frequently Asked Questions
What does PACCAR SPN 111 FMI 5 mean?
It indicates a Coolant Level fault: Current Below Normal or Open Circuit. Confirm with live data and wiring tests before parts replacement.
Can SPN 111 cause a derate?
It can contribute to limp behavior if the ECM loses trust in critical data, especially when paired with other faults.
What tools diagnose this best?
PACCAR Davie and Noregon JPRO, plus a quality multimeter and mechanical gauges for pressure/temperature checks.
Should I clear the code first?
No. Capture freeze-frame and the full stack first. Clear only after the repair and verification.
More PACCAR codes on this system
- PACCAR SPN 111 FMI 1 — Engine Coolant Level Sensor
- PACCAR SPN 111 FMI 3 — Engine Coolant Level Sensor Circuit
- Paccar SPN 94 FMI 18 — Fuel Delivery Pressure Sensor
- Paccar SPN 1231 FMI 4 — Fuel Rail Pressure
- PACCAR SPN 5246 FMI 16 — SCR System
- Paccar SPN 190 FMI 0 — Engine Speed Sensor Circuit
- Paccar SPN 102 FMI 2 — Boost Pressure Sensor Circuit
- Paccar SPN 4094 FMI 16 — DPF Soot Load
Guides that go deeper
- SPN 1569 FMI 31: Engine Protection Shutdown and Safe Recovery Steps [2026 Diagnostic Guide]
SPN 1569 FMI 31 means engine protection shutdown is active—not the root fault. Read stacked codes, verify oil and coolant, then reset only after the trigger is fixed.
- Detroit DDDL Basics: Finding the Root Code Behind a Derate
Use Detroit DDDL the right way: separate root SPN/FMI faults from inducement result codes, read derate stage data, and stop replacing parts on guesses.
- How to Capture a Useful Fault Stack Before the Shop Clears Codes
How drivers and techs can capture a useful fault stack—SPNs, FMIs, freeze-frame, and counts—before anyone clears codes and erases the diagnosis.