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SPN 3242 FMI 2

Aftertreatment 1 DPF Intake Gas Temperature — Data erratic, intermittent, or incorrect.
The signal jumps around, drops in and out, or disagrees with other information the controller has.

What the SPN covers: Exhaust temperature entering the diesel particulate filter. More on SPN 3242.

What FMI 2 usually points to: Loose or corroded connectors, chafed wiring, a failing sensor, or two redundant sensors that do not agree. More on FMI 2.

Severity

MEDIUM — fix soon

Regenerations may be blocked until fixed, leading to soot buildup.

Likely causes

  1. Failed exhaust temperature sensor
  2. Wiring damage from heat
  3. Diesel oxidation catalyst not lighting off

Checks & fixes (easiest first)

  1. Compare all exhaust temperature sensors at idle after a cold soak
  2. Inspect wiring for heat damage
  3. Check DOC performance during a regen

FAQ

What does SPN 3242 FMI 2 mean?

Aftertreatment 1 DPF Intake Gas Temperature — data erratic, intermittent, or incorrect. The signal jumps around, drops in and out, or disagrees with other information the controller has.

Is SPN 3242 FMI 2 serious?

Regenerations may be blocked until fixed, leading to soot buildup.

What should I check first for SPN 3242 FMI 2?

Compare all exhaust temperature sensors at idle after a cold soak; Inspect wiring for heat damage; Check DOC performance during a regen.