ISX12/ISX11.9 CM2250 Fault Code: 3318 | SPN: 3242 | FMI: 2Aftertreatment 1 Diesel Particulate Filter Intake Temperature – Data Erratic, Intermittent, or Incorrect

Overview

Circuit Description

The aftertreatment temperature sensors are used by the engine control module (ECM) to monitor the engine exhaust temperatures in the aftertreatment system. The aftertreatment temperature sensors are thermistors and change resistance based on the temperature being measured. The ECM provides a 5 volt reference voltage to the sensor. The ECM monitors the change in signal voltage and converts this to a temperature value.

When the exhaust temperature is cold, the sensor or thermistor resistance is high. The ECM signal voltage only pulls down a small amount through the sensor to ground. Therefore, the ECM senses a high signal voltage or low temperature. When the exhaust gas temperature is hot, 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 aftertreatment diesel particulate filter intake temperature sensor is located in the aftertreatment system. It is located at the outlet of the diesel oxidation catalyst and before the diesel particulate filter. Refer to the original equipment manufacturer (OEM) service manual.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position and the engine is running.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) detected the difference between the aftertreatment diesel particulate filter intake temperature sensor data and diesel particulate filter outlet temperature sensor data did not match the expected value for the present engine operating conditions.

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.

A default value for the aftertreatment diesel particulate filter intake temperature reading is used.

• Diesel exhaust fluid injection into the aftertreatment system is disabled.

Active and stationary regeneration of the diesel particulate filter will be disabled.

Exhaust gas recirculation (EGR) valve operation will be disabled.

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 type driving and steady state highway type 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, utilize a routine that incorporates acceleration and motoring events, steady state highway type operation, and load. This will simulate normal driving and allow the diagnostics in the ECM to run.
• The fault code status displayed by the recommended Cummins® electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
• The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
• For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where the diagnostic runs and passes.
• The “Reset All Faults” command in the recommended Cummins® electronic service tool or equivalent 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 aftertreatment diesel particulate filter intake temperature sensor

A malfunctioning aftertreatment diesel particulate filter outlet temperature sensor

High resistance in the aftertreatment diesel particulate filter intake temperature sensor signal or return lines

Malfunctioning aftertreatment diesel particulate filter temperature sensor interface module.

Reference the appropriate OEM wiring diagram when troubleshooting circuits that utilize wiring supplied by the OEM.

For intermittent power supply and datalink communication issues with Aftertreatment Components, it is highly recommended that the OEM Power Distribution Center fuses and relays be thoroughly checked for loose, missing or intermittent connections.