Detroit Diesel Fault Code
Free · no signupSPN 3226 FMI 20
Check Engine Light / Inducement Risk
System
Emissions / NOx
Symptom
Check Engine Light / Inducement Risk
Diagnosis & fix steps
LOGIC: Outlet NOx Sensor Signal Drifted High (Data Implausible).
ACTION: Inspect outlet NOx sensor probe face for soot/oil contamination. Check 24V power supply and CAN bus lines; perform NOx sensor calibration via DiagnosticLink.
Red Seal field insights
Closed Loop Control: The ACM uses downstream NOx telemetry to verify SCR efficiency; a drifted sensor skews conversion calculations and triggers inducement counters.
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