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

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

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

Conditions for Setting the Fault CodesThe ECM detects that engine speed is 50 rpm below governed idle speed for 30 seconds.

Action Taken When the Fault Code is ActiveThe ECM illuminates the amber CHECK ENGINE lamp and/or the MIL after this diagnostic fails on two consecutive trips.

Conditions for Clearing the Fault CodeTo validate the repair, start the engine and let it idle for 1 minute.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 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 TalkPossible causes of this fault code include:

Fuel system malfunctionCrankshaft position sensor malfunctionCamshaft position sensor malfunctionIncreased engine accessory load

Possible Cause:1) Crankshaft engine speed sensor2) Camshaft engine position sensor3) ECM calibration