DOC (Diesel Oxidation Catalyst) Inlet NOx Sensor - Data Drifted High
The JD-SPN3216-FMI20 (John Deere PowerTech) diesel fault code means: DOC (Diesel Oxidation Catalyst) Inlet 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 NOx sensor
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Common Symptoms
- SCR efficiency derate after ~50 hrs of operation
- 'DEF Quality' or 'Aftertreatment' amber warning
Probable Causes (Ranked by Likelihood)
- Inlet NOx sensor contaminated (soot/DEF crystal build-up) Very Likely
- Sensor heater failing Likely
Step-by-Step Diagnostic Procedure
Run NOx sensor calibration in Service ADVISOR; replace if heater element is open.
Frequently Asked Questions
What is John Deere fault code SPN 3216 FMI 20?
On John Deere PowerTech engines, SPN 3216 FMI 20 means: DOC (Diesel Oxidation Catalyst) Inlet NOx Sensor - Data Drifted High. Moderate code. Keep working cautiously and plan repair.
Can I keep using my John Deere tractor with SPN 3216 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 3216 FMI 20?
Repair cost range: $650-$1,400 NOx sensor. 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.
SPN3216-FMI20 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown: