EGR Valve Position - Voltage Below Normal or Shorted to Low Source
What does JD-SPN2791-FMI4 mean?
The JD-SPN2791-FMI4 (John Deere PowerTech) diesel fault code means: EGR Valve Position - Voltage Below Normal or Shorted to Low Source. This is a moderate severity code.
Common Symptoms
- Lack of throttle response
- Black smoke under load
- EGR-related derate on aftertreatment models
Probable Causes (Ranked by Likelihood)
- Carbon packed on EGR valve seat Very Likely
- EGR cooler internal leak (coolant in intake) Possible
- EGR position sensor out of calibration Likely
- EGR actuator stepper motor failure Possible
Step-by-Step Diagnostic Procedure
Service ADVISOR EGR sweep test -- confirm actual vs. desired vane/valve position.
Pressure-test EGR cooler for coolant leak if coolant loss is unexplained.
Inspect intake for excessive carbon build-up; scrape if >3/8 inch.
Check for exhaust back-pressure out of spec causing EGR hang-up.
Frequently Asked Questions
What is John Deere fault code SPN 2791 FMI 4?
On John Deere PowerTech engines, SPN 2791 FMI 4 means: EGR Valve Position - Voltage Below Normal or Shorted to Low Source. Moderate code -- diagnose soon; continued operation may increase repair scope.
Can I keep using my John Deere tractor with SPN 2791 FMI 4?
Moderate fault -- you can usually keep working but expect derate if aftertreatment-related. Diagnose with John Deere Service ADVISOR via an EDL v3 / CF3 interface.
How much does it cost to fix John Deere SPN 2791 FMI 4?
Repair cost range: $180-$650 EGR valve or cooler cleaning, $900-$2,400 cooler R&R. Dealer labor on large tractors runs $180-$240/hr in 2026.