SCR Outlet NOx Sensor - Data Drifted High
The JD-SPN3226-FMI20 (John Deere PowerTech) diesel fault code means: SCR Outlet NOx Sensor - Data Drifted High. This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- intermediate
- Estimated cost
- $650-$1,400 sensor, $3,500-$6,500 SCR
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Common Symptoms
- Inducement timer active if not cleared
- Final rate low at SCR outlet
Probable Causes (Ranked by Likelihood)
- Outlet NOx sensor failed / contaminated Very Likely
- SCR catalyst aged Possible
Step-by-Step Diagnostic Procedure
Compare outlet NOx to inlet NOx; outlet should read ~10% of inlet at normal SCR temp.
Replace outlet NOx sensor first; re-test before condemning SCR.
Frequently Asked Questions
What is John Deere fault code SPN 3226 FMI 20?
On John Deere PowerTech engines, SPN 3226 FMI 20 means: SCR Outlet NOx Sensor - Data Drifted High. Moderate code. Keep working cautiously and plan repair.
Can I keep using my John Deere tractor with SPN 3226 FMI 20?
Moderate fault -- continue light use, fix at next service. Diagnose with John Deere Service ADVISOR via an EDL v3 / CF3 interface.
How much does it cost to fix John Deere SPN 3226 FMI 20?
Repair cost range: $650-$1,400 sensor, $3,500-$6,500 SCR. Dealer labor on large tractors runs $180-$240/hr in 2026.
Sources
This page is built from documented references. Verify against your own service info before repair work.
SPN3226-FMI20 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: