Aftertreatment SCR Outlet Temperature - Voltage Above Normal or Shorted to High Source
The JD-SPN4363-FMI3 (John Deere PowerTech) diesel fault code means: Aftertreatment SCR Outlet Temperature - Voltage Above Normal or Shorted to High Source. This is a moderate severity code.
- Keep driving?
- Reduced power (derate)
- DIY difficulty
- advanced
- Estimated cost
- $260-$780 NOx sensor / SCR temp sensor, $3,500-$7,500 SCR catalyst
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Common Symptoms
- SCR NOx-efficiency fault, derate within one drive cycle if persistent
- Low tailpipe NOx conversion at operating temp
- Dealer-inducement warnings on Tier 4 Final machines
Probable Causes (Ranked by Likelihood)
- Upstream / downstream NOx sensor drift Likely
- SCR inlet / outlet temperature sensor failure Likely
- SCR substrate poisoning (wrong DEF) or thermal damage Possible
- Exhaust leak upstream of SCR disturbing sensor reading Possible
Frequently Asked Questions
What is John Deere fault code SPN 4363 FMI 3?
On John Deere PowerTech engines, SPN 4363 FMI 3 means: Aftertreatment SCR Outlet Temperature - Voltage Above Normal or Shorted to High Source. Moderate code -- diagnose soon; continued operation may increase repair scope.
Can I keep using my John Deere tractor with SPN 4363 FMI 3?
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 4363 FMI 3?
Repair cost range: $260-$780 NOx sensor / SCR temp sensor, $3,500-$7,500 SCR catalyst. Dealer labor on large tractors runs $180-$240/hr in 2026.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
Record SCR inlet vs. outlet temperature during steady-state high idle.
Use Service ADVISOR SCR efficiency test -- compare to CTM acceptance band.
Inspect clamps / V-bands between turbo and SCR for leaks.
If substrate is damaged, only a full catalyst module replacement will clear the code.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
Commonly Affected Vehicles
- 2015+ John Deere 7R Series (7210R, 7250R, 7290R, 7310R)
- 2015+ John Deere 8R / 8RT Series (8245R-8370R)
- John Deere S670 / S680 / S690 combines
- John Deere S770 / S780 / S790 combines
- 2021+ John Deere X9 1000 combine
- John Deere 1025R sub-compact utility tractor
- John Deere 2025R / 2038R / 2032R compact utility tractors
- John Deere R4045 / R4060 self-propelled sprayers
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