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SPN 3242 FMI 0

Aftertreatment 1 DPF Intake Gas Temperature — Value too high (most severe).
The reading is valid but far above the normal operating range — high enough that the controller treats it as the most serious level of 'too high'.

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

What FMI 0 usually points to: A real over-condition (over-temperature, over-pressure, overspeed) or a sensor reporting a believable but wrong high value. More on FMI 0.

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 0 mean?

Aftertreatment 1 DPF Intake Gas Temperature — value too high (most severe). The reading is valid but far above the normal operating range — high enough that the controller treats it as the most serious level of 'too high'.

Is SPN 3242 FMI 0 serious?

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

What should I check first for SPN 3242 FMI 0?

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