Cummins ISX12 CM2250 (2010-12) Fault Code: 3342 PID: 91 SPN: 4752 FMI: 18 Engine Exhaust Gas Recirculation Cooler Efficiency- Data Valid But Below Normal Operating Range- Moderately Severe Level

Circuit Description
The exhaust gas recirculation (EGR) temperature sensor is a variable resistor sensor and is used to measure the temperature of the EGR gas flow after it exits the EGR cooler. The engine control module (ECM) supplies 5 volts to the EGR temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature.

The EGR temperature value is used by the ECM to determine the efficiency of the EGR cooler.

Component Location
The EGR temperature sensor is located on the EGR connection tube between the EGR valve and the air intake connection.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the engine is operating.

Conditions for Setting the Fault Codes
The ECM detects that the EGR temperature is greater than a threshold for 5 seconds.

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.

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 tINSITE? 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:

A malfunctioning EGR temperature sensor
A malfunctioning EGR cooler.

Possible Cause:
1) Cooling System
2) ECM failure