Cummins ISX12 CM2250 (2010-12) Fault Code: 1866 PID: 411 SPN: 411 FMI: 2 Exhaust Gas Recirculation Valve Delta Pressure- Data Erratic, Intermittent, or Incorrect

Circuit Description
The EGR differential pressure sensor has two ports that sense exhaust pressure. The sensor outputs a voltage which represents the pressure difference between the two ports located across an orifice in the EGR tube. The engine control module (ECM) uses this pressure to determine how much exhaust gas is flowing in the EGR connection tube to the intake manifold. This information is used to control the EGR valve for correct emission levels.The ECM provides a 5 volt supply to the EGR differential pressure sensor on the sensor supply circuit. The ECM also provides a ground on the sensor return circuit. The EGR differential pressure sensor provides a signal to the ECM on the EGR differential pressure sensor signal circuit. This sensor signal voltage changes, based on the differential pressure in the EGR crossover tube.The EGR differential pressure sensor measures the exhaust gas pressure drop across the EGR differential pressure orifice. This pressure drop is used to calculate the amount of EGR flow into the intake manifold.

Component Location
The sensor is located near the air intake.

Conditions for Running the Diagnostics
This diagnostic runs at key OFF when the following conditions are met:

Engine coolant temperature is 67?C [154?F] or higher.
Intake manifold air temperature is 7?C [44?F] or higher.
Keyswitch transitions from ON to OFF.
Conditions for Setting the Fault Codes
The fault code is set active when the EGR differential pressure sensor is reading higher or lower than a calibratible value when the keyswitch is turned OFF.

Action Taken When the Fault Code is Active
The ECM illuminates the amber CHECK ENGINE lamp and/or malfunction indicator lamp (MIL) at key on when the diagnostic runs and fails.
Diesel exhaust fluid injection into the aftertreatment system is disabled.
Active and stationary regeneration of the diesel particulate filter will be disabled.
The EGR valve will be closed.
Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
Conditions for Clearing the Fault Code
To validate the repair using a Diagnostic Road Test, utilize a route that incorporates both stop-and-go city driving and steady state highway driving. It may be necessary to load the unit for certain diagnostics in the ECM to run.
To validate the repair using a Chassis Dynamometer Test, utilize a routine that incorporates acceleration and motoring events, steady state highway operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
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 Diagnostics (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
This check is only performed at keyswitch OFF, during the ECM powerdown. During this diagnostic check, the ECM monitors the value of the EGR differential pressure sensor. If this value is outside of a specified range, Fault Code 1866 is set active.

Possible causes of this fault code include:

A damaged EGR differential pressure sensor.
High resistance in the wiring harness on the SIGNAL or RETURN wire.
Plugged or restricted EGR differential pressure sensor flow ports.

Possible Cause:
1) ECM failure