SPN 3226 FMI 2 is the Detroit DD Series fault-code procedure for an SCR outlet NOx sensor drift fault. This 1-page diagnostic PDF documents the fault, its monitored circuit on the SCR outlet NOx sensor, and the exact troubleshooting steps a technician follows to confirm and repair the failure.
Official document details
| Brand | Detroit |
| Model coverage | DD Series (EPA 2007-Current); Series 60 DDEC VI |
| System / Group | DD Series / DTCs |
| SPN (fault code) | 3226 |
| FMI (failure mode) | 2 |
| Emission family | EPA10 / GHG14 calibration |
| Source | Detroit Power Service Literature (Copyright © 2017) |
| Pages | 1 |
| File size | 0.21 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (SPN 3226, failure mode 2)
- Troubleshooting steps
- Aftertreatment leak inspection
- High-idle regeneration and log submission
Applicable truck models
This procedure applies to Detroit DD13, DD15 and DD16 engines in the DD Series (EPA 2007-Current) range and the equivalent Series 60 (DDEC VI) platform, as fitted to Freightliner and Western Star trucks. Confirm the EPA10 / GHG14 emission family matches the truck before following the steps; full model and coverage data is published on the Detroit official website.
Who needs this SPN 3226 FMI 2 manual
Diesel technicians, fleet workshops and mobile mechanics diagnosing an SCR outlet NOx sensor drift code on EPA10 or GHG14 Detroit engines need this reference to test the circuit correctly with a diesel diagnostic tool instead of replacing parts by guesswork.
SPN 3226 FMI 2 repair steps explained
The technician checks the Aftertreatment System (ATS) for visible exhaust leaks or damage, connects a diesel diagnostic tool, then disconnects the Diesel Exhaust Fluid (DEF) metering unit dosing valve on EPA10 or the dosing unit on GHG14. A high-idle regeneration is performed and the retained log file is submitted to the Detroit Customer Support Center at 800-445-1980 for analysis. SPN 3361/5, which sets with the valve unplugged, is disregarded during this test.
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