Aftertreatment DOC Intake Temperature - Voltage Below Normal or Shorted to Low Source
What does JD-SPN4765-FMI4 mean?
The JD-SPN4765-FMI4 (John Deere PowerTech) diesel fault code means: Aftertreatment DOC Intake Temperature - Voltage Below Normal or Shorted to Low Source. This is a moderate severity code.
Common Symptoms
- Active regen failure or abnormally long regen time
- DOC temperature sensor fault on operator display
- Elevated tailpipe HC / CO emissions
Probable Causes (Ranked by Likelihood)
- DOC inlet / outlet temp sensor failure Likely
- Soot contamination on thermocouple tip Likely
- DOC face plugged by unburnt fuel from injector leak Possible
- HC doser / 7th injector soot build-up on the upstream side Possible
Step-by-Step Diagnostic Procedure
Watch DOC inlet vs. outlet Δ during active regen -- should rise >100 °C.
Inspect DOC substrate for melt / glazing -- requires replacement.
Clean or replace the DOC temperature sensor harness and thermocouple.
Inspect HC doser or 7th injector fuel pattern.
Frequently Asked Questions
What is John Deere fault code SPN 4765 FMI 4?
On John Deere PowerTech engines, SPN 4765 FMI 4 means: Aftertreatment DOC Intake Temperature - 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 4765 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 4765 FMI 4?
Repair cost range: $260-$780 DOC temp sensor, $2,800-$6,000 DOC replacement. Dealer labor on large tractors runs $180-$240/hr in 2026.