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SPN 111 FMI 1 — Coolant level — low

What it means: Coolant level — low.

How serious / can you keep driving: Critical. Stop as soon as it's safe.

Check first: Check level immediately

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CriticalCoolingStop as soon as it's safe

Applies to: Detroit · Paccar · Volvo

What SPN 111 FMI 1 means

Coolant level — low.

How serious is it?

Critical. Stop as soon as it's safe.

Most likely causes

  1. Coolant leak
  2. Sensor failure
  3. Leak
  4. Sensor

First moves (roadside)

  1. Check level immediately
  2. Inspect for leaks
  3. Verify level

FAQ

What does SPN 111 FMI 1 mean?

Coolant level — low.

How serious is SPN 111 FMI 1?

Critical — Stop as soon as it's safe.

What's the most likely cause of SPN 111 FMI 1?

The most common cause is: Coolant leak. Other possibilities include Sensor failure; Leak; Sensor.

Can I keep driving with SPN 111 FMI 1?

Stop as soon as it's safe. When in doubt, get a qualified mobile diesel tech on the truck before continuing.

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Related codes

Codes that commonly appear alongside SPN 111 FMI 1, or share the same subsystem.

Same symptom: Running hot

Other codes that show up as coolant temperature climbing or a hot-engine lamp.

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General diagnostic guidance for heavy-duty diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack). Not a substitute for a scan-tool diagnosis on your specific truck.