Detroit DD15 GHG14 (2014-16) Fault Code: SPN 3216 FMI 21 (ACM) SCR NOx Inlet Sensor Drift Low

DESCRIPTION:
Selective catalyst reduction (SCR) inlet NOx sensor – drift (low box).

MONITORED PARAMETER:
Engine out NOx.

TYPICAL ENABLING CONDITIONS:
1. Exhaust gas recirculation (EGR) mass flow greater than .08 kg/s.
2. Engine speed is between 1450-1900 rpm.
3. Engine torque is between 1400-2100 N·m (1033 to 1549 lb·ft).
4. Battery voltage greater than 11 vDC.
5. Coolant temperature greater than 65°C (149°F).
6. Ambient temperature greater than -8°C (17.6°F) ambient.
7. Barometric pressure greater than 755 mbar.
8. Engine is not in regeneration mode.

MONITOR SEQUENCE:
None

EXECUTION FREQUENCY:
Always enabled

TYPICAL DURATION:
1.2 seconds

DASH LAMPS:
MIL

ENGINE REACTION:
None

VERIFICATION:
1. Warm up engine such that coolant temperature greater than 65°C (149°F).
2. Ensure engine is not in regeneration mode.
3. Ensure ambient temperature greater than -8°C (18°F) barometric pressure greater than 755 mbar.

NOTE: If any other EGR codes are active, fix those first.

PROBABLE CAUSES:
1. Inspect the entire air inlet system, charge air cooler, and EGR piping/hoses.
2. Check for failed injector.
3. Check the aftertreatment system for leaks/damage.
4. Perform a high idle regeneration.