Cummins X15 CM2450 X124B (2018 & Newer) Fault Code: 3748 PID: SPN: 3216 FMI: 20 Aftertreatment 1 Intake Nox Sensor- Data Not Rational- Drifted High
The aftertreatment intake NOx (nitrogen oxides) sensor is a smart device and communicates with the engine control module (ECM) via the J1939 data link. The aftertreatment intake NOx sensor performs internal diagnostics and reports malfunctions back to the primary ECM using the J1939 data link. The NOx sensor is permanently attached to the NOx control module. They are serviced as a single component and can not be replaced individually. The aftertreatment intake NOx sensor is used to measure the NOx emissions at the intake of the aftertreatment system.
The aftertreatment intake NOx sensor is mounted on the engine near the turbocharger turbine outlet.
Conditions for Running the Diagnostics
This diagnostic runs when the aftertreatment diesel oxidation catalyst intake temperature is above 150°C [302°F], and the engine is in a motoring condition.
Conditions for Setting the Fault Codes
The Engine Control Module (ECM) detected the aftertreatment intake NOx sensor was not reading zero while in a motoring (non-fueling) condition.
Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or Malfunction Indicator Lamp (MIL) after the diagnostic fails on two consecutive trips.
Diesel exhaust fluid injection into the aftertreatment system is disabled.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Engine torque will be severely reduced.
Vehicle speed will be limited to 8 km [5 mi] per hour after extended engine operation with the fault code active.
Conditions for Clearing the Fault Code
To validate the repair, start and operate the engine to raise exhaust temperatures. This can be done by performing a road test.
The aftertreatment diesel oxidation catalyst intake temperature must be above 150° C [302° F] for 5 seconds, and the engine must be in a motoring condition before the aftertreatment intake NOx sensor can run its internal diagnostics.
The fault code status displayed by INSITE™ electronic service tool will change to INACTIVE immediately after the diagnostic runs and passes.
The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
The Reset All Faults command in INSITE™ electronic service tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.
Possible causes of this fault code include:
Malfunctioning aftertreatment intake NOx sensor
Improperly installed aftertreatment intake NOx sensor.
1) Aftertreatment intake NOx sensor failure
2) ECM calibration
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