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SPN 3246 FMI 3 — DPF outlet temp sensor — voltage high

What it means: DPF outlet temp sensor — voltage high.

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

Check first: Start with the most likely cause: Open sensor.

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SeriousAftertreatment & EmissionsPower derate likely — plan to stop soon

Applies to: Detroit

What SPN 3246 FMI 3 means

DPF outlet temp sensor — voltage high.

How serious is it?

Serious. Power derate likely — plan to stop soon.

Most likely causes

  1. Open sensor
  2. Open wire

FAQ

What does SPN 3246 FMI 3 mean?

DPF outlet temp sensor — voltage high.

How serious is SPN 3246 FMI 3?

Serious — Power derate likely — plan to stop soon.

What's the most likely cause of SPN 3246 FMI 3?

The most common cause is: Open sensor. Other possibilities include Open wire.

Can I keep driving with SPN 3246 FMI 3?

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 3246 FMI 3, or share the same subsystem.

Same symptom: Regen problems

Other codes that block a regen or come back as soot load climbing.

All Aftertreatment & Emissions 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.