JD-SPN3226-FMI20 moderate John Deere PowerTech ›

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.

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Keep driving?
Yes, with caution
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

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.

Mechanics Guide Step-by-step diagnosis

Step-by-Step Diagnostic Procedure

  1. Compare outlet NOx to inlet NOx; outlet should read ~10% of inlet at normal SCR temp.

  2. Replace outlet NOx sensor first; re-test before condemning SCR.

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)

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:

Volvo / Mack serious SCR Outlet NOx Sensor Drift High (J1939)

Commonly Affected Vehicles

  • 2014+ John Deere 6R Series tractors
  • 2015+ John Deere 7R Series tractors
  • 2015+ John Deere 8R / 8RT Series tractors
  • 2015+ John Deere 9R / 9RT / 9RX Series tractors
  • 2015+ John Deere S670 / S680 / S690 combines
  • John Deere S770 / S780 / S790 combines
  • John Deere 544/644/724 wheel loaders (construction)
  • John Deere 310/410 backhoes

Explore More

More John Deere PowerTech codes → Diesel home All diesel codes Heavy-duty Guides

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