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SPN 100 FMI 4 — Oil pressure sensor — voltage low

SeriousEnginePower derate likely — plan to stop soon

Applies to: Detroit · Navistar · Paccar · Volvo

Oil pressure sensor — voltage low.

Don't risk it — get a diesel tech on the truck.

Your SPN/FMI rides along, so nearby mechanics see the fault before they quote you.

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How serious is it?

Serious. Power derate likely — plan to stop soon.

Most likely causes

  1. Signal short to ground
  2. Failed sensor
  3. Short ground
  4. Short to ground
  5. Signal to ground

First moves (roadside)

  1. Unplug — fault should invert
  2. Unplug — invert

FAQ

What does SPN 100 FMI 4 mean?

Oil pressure sensor — voltage low.

How serious is SPN 100 FMI 4?

Serious — Power derate likely — plan to stop soon.

What's the most likely cause of SPN 100 FMI 4?

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

Can I keep driving with SPN 100 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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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.