Cummins ISX12 CM2250 (2010-12) Fault Code: 3343 PID: SPN: 5285 FMI: 18 Engine Charge-Air Cooler Efficiency- Data Valid But Below Normal Operating Range- Moderately Severe Level

Circuit Description
The intake manifold 1 temperature sensor is a variable resistor sensor and is used to measure the temperature of the air entering the intake manifold of the engine. The electronic control module (ECM) supplies 5 volts to the intake manifold temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the intake manifold temperature.

When the intake air is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to a ground. Therefore, the ECM senses a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. The signal voltage pulls down a large amount. Therefore, the ECM senses a low signal voltage, or a high temperature.

Component Location
The intake manifold 1 temperature sensor is located in the air intake manifold.

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

Conditions for Setting the Fault Codes
The ECM detects that the intake manifold temperature is greater than 111?C [232?F] 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, start the engine and let it idle for 5 minutes.
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 Talk
Possible causes of this fault include:

A malfunctioning intake manifold temperature sensor
A malfunctioning charge-air cooler.

Possible Cause:
1) Intake Manifold air temperature sensor failure
2) ECM calibration