Home › Codes › SPN 27 › FMI 4

SPN 27 FMI 4

EGR Valve Position — Voltage below normal or shorted low.
The sensor circuit voltage is lower than it should ever be, usually near zero.

What the SPN covers: Tracks how far open the exhaust gas recirculation (EGR) valve is compared with where the engine computer asked it to be. More on SPN 27.

What FMI 4 usually points to: Signal wire shorted to ground, a lost 5 V reference, or an open signal wire on a pulled-down circuit. More on FMI 4.

Severity

MEDIUM — fix soon

Usually drivable short-term, but expect a derate and more soot. Get it checked soon.

Likely causes

  1. Wiring or connector fault in this circuit (most common for electrical FMIs)
  2. Carbon-stuck or sticking EGR valve
  3. Failed EGR actuator or position sensor
  4. Wiring or connector damage near the hot side of the engine
  5. Low supply voltage to the actuator

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. Inspect EGR connector and harness for heat damage
  4. Command the EGR valve with a scan tool and watch actual vs. commanded position
  5. Remove and inspect for carbon if it is slow or stuck
  6. Check related EGR temperature and DPF codes

FAQ

What does SPN 27 FMI 4 mean?

EGR Valve Position — voltage below normal or shorted low. The sensor circuit voltage is lower than it should ever be, usually near zero.

Is SPN 27 FMI 4 serious?

Usually drivable short-term, but expect a derate and more soot. Get it checked soon.

What should I check first for SPN 27 FMI 4?

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; Inspect EGR connector and harness for heat damage.