Aftertreatment SCR Outlet Temperature - Data Valid but Above Normal Operational Range (Moderately Severe)
What does JD-SPN4363-FMI16 mean?
The JD-SPN4363-FMI16 (John Deere PowerTech) diesel fault code means: Aftertreatment SCR Outlet Temperature - Data Valid but Above Normal Operational Range (Moderately Severe). This is a moderate severity code.
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
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.
Frequently Asked Questions
What is John Deere fault code SPN 4363 FMI 16?
On John Deere PowerTech engines, SPN 4363 FMI 16 means: Aftertreatment SCR Outlet Temperature - Data Valid but Above Normal Operational Range (Moderately Severe). Moderate code -- diagnose soon; continued operation may increase repair scope.
Can I keep using my John Deere tractor with SPN 4363 FMI 16?
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 16?
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.