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SPN 412 FMI 3

EGR Temperature — Voltage above normal or shorted high.
The sensor circuit voltage is higher than it should ever be, usually pegged near the supply voltage.

What the SPN covers: Temperature of recirculated exhaust gas after the EGR cooler. More on SPN 412.

What FMI 3 usually points to: Signal wire shorted to the 5 V reference or battery, an open ground, or an unplugged sensor on a pulled-up circuit. More on FMI 3.

Severity

MEDIUM — fix soon

High EGR temperature often means the EGR cooler is not cooling. Address soon to avoid further damage.

Likely causes

  1. Wiring or connector fault in this circuit (most common for electrical FMIs)
  2. Plugged or failing EGR cooler
  3. Low coolant flow through the EGR cooler
  4. EGR valve stuck open
  5. Sensor or wiring fault

Checks & fixes (easiest first)

  1. Inspect the connector and harness for this circuit: corrosion, water, chafing, backed-out pins
  2. Check the reference voltage, ground and signal at the component per OEM pin-out
  3. Check coolant level and look for coolant loss
  4. Inspect EGR cooler for plugging or leaks
  5. Check EGR valve operation
  6. Compare sensor reading after cold soak

FAQ

What does SPN 412 FMI 3 mean?

EGR Temperature — voltage above normal or shorted high. The sensor circuit voltage is higher than it should ever be, usually pegged near the supply voltage.

Is SPN 412 FMI 3 serious?

High EGR temperature often means the EGR cooler is not cooling. Address soon to avoid further damage.

What should I check first for SPN 412 FMI 3?

Inspect the connector and harness for this circuit: corrosion, water, chafing, backed-out pins; Check the reference voltage, ground and signal at the component per OEM pin-out; Check coolant level and look for coolant loss.