2020 International LT - SPN 3216 FMI 20 (Inlet NOx Sensor Drift)

Question

My 2020 International LT is throwing an SPN 3216 FMI 20 code. The truck runs fine, no derate yet, but the Malfunction Indicator Lamp stays on. From what I've read, this is the Intake NOx sensor reading out of range compared to the Outlet sensor.

I really don't want to spend $600 on a sensor if it's just a wiring issue or something else. I've cleaned the connector with contact cleaner, but the light comes back after about 50 miles. Anyone seen this on the X15 specifically?

DPF_Doc · Accepted Answer

✅ Confirmed fix: It's rarely a dead sensor when you get a 'drift' code. Usually, it's an exhaust leak at the turbo V-band clamp or the flex pipe. Even a tiny pinhole leak will introduce fresh air, tricking the intake NOx sensor into thinking the engine is running leaner/cleaner than it is. I replaced the flex pipe that had a small crack under the heat shield, and the code cleared itself.

JeepJunkieJoe · Answer

Swap the front and rear NOx sensors to see if the code moves. If it changes to an Outlet NOx code, then you know for sure the sensor is the problem. They are the same part number on many of these X15s.

2020 International LT - SPN 3216 FMI 20 (Inlet NOx Sensor Drift)

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