Cummins ISX12 CM2250 (2010-12) Fault Code: 3715 PID: SPN: 188 FMI: 16 Engine Speed At Idle- Data Valid But Below Normal Operating Range- Moderately Severe Level

Circuit Description
The Electronic Control Module (ECM) continuously monitors the engine speed at idle and adjusts fueling to maintain governed idle speed.

Component Location
The engine speed is monitored by the crankshaft and/or camshaft position sensors.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is operating at idle and the PTO is not active.

Conditions for Setting the Fault Codes
The ECM detects that engine speed is 50 rpm above governed idle speed for 30 seconds.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or the Malfunction Indicator Lamp (MIL) after this diagnostic fails on two consecutive trips.

Conditions for Clearing the Fault Code
To validate the repair, start the engine and let it idle for 1 minute.
The fault code status displayed by the 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 after the diagnostic runs and passes.
For On-Board Diagnostic (OBD) engines, the ECM will turn off the 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.

Shop Talk
Possible causes of this fault code include:

Fuel system malfunction
Crankshaft position sensor malfunction
Camshaft position sensor malfunction
Alternate fuel source entering intake system

Possible Cause:
1) Crankshaft position sensor or camshaft engine position sensor
2) ECM calibration