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SPN 105 FMI 4 — Intake manifold temp — voltage low

What it means: Intake manifold temp — voltage low.

How serious / can you keep driving: Serious. Power derate likely — plan to stop soon.

Check first: Unplug — invert

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SeriousEnginePower derate likely — plan to stop soon

Applies to: Detroit · Navistar · Paccar · Volvo

What SPN 105 FMI 4 means

Intake manifold temp — voltage low.

How serious is it?

Serious. Power derate likely — plan to stop soon.

Most likely causes

  1. Short to ground
  2. Failed sensor
  3. Short ground

First moves (roadside)

  1. Unplug — invert

FAQ

What does SPN 105 FMI 4 mean?

Intake manifold temp — voltage low.

How serious is SPN 105 FMI 4?

Serious — Power derate likely — plan to stop soon.

What's the most likely cause of SPN 105 FMI 4?

The most common cause is: Short to ground. Other possibilities include Failed sensor; Short ground.

Can I keep driving with SPN 105 FMI 4?

Power derate likely — plan to stop soon. 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 105 FMI 4, or share the same subsystem.

Same symptom: Charging and voltage

Other codes that trace back to voltage — one bad ground can set half a dozen of them at once.

All Engine codes

Find a mechanic or related guides

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.