Inlet NOx sensor drifted
The value crept upward over time compared with where it should sit. Slow drift, not a sudden fault.
SPN 3216 — Inlet NOx sensor drifted
SPN 3216 is the parameter the ECM is flagging on International engines. The FMI that comes with it tells you how it failed. Each failure mode below has its own causes and its own test order — do not treat them as the same repair.
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