CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2639

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Overview

ISX and ISM – Aftertreatment System SMALL | MEDIUM | LARGE

Circuit Description

The engine aftertreatment system monitors the soot load in the aftertreatment diesel particulate filter. Under normal operating conditions, the aftertreatment diesel particulate filter is self-cleaning, where soot is converted to carbon dioxide, nitrogen, and water. Under light load operating conditions it may be necessary to preform a stationary regeneration of the aftertreatment diesel particulate filter. The soot load in the aftertreatment diesel particulate filter is estimated using the aftertreatment differential pressure sensor and the calculated soot output of the engine.

This fault code can be triggered if the application is not operating at duty cycle high enough to regenerate the aftertreatment diesel particulate filter. This fault code indicates that the exhaust temperatures exiting the turbocharger are not high enough to actively regenerate the soot that is trapped in the aftertreatment diesel particulate filter. It may be necessary to increase the duty cycle of the application in order to prevent plugging of the aftertreatment diesel particulate filter.

Component Location

The aftertreatment diesel particulate filter is located in the exhaust system and is installed by the original equipment manufacturer (OEM). Refer to the OEM troubleshooting and repair manual.

Conditions for Running the Diagnostics

This diagnostic runs continuously when engine speed is greater than 500 rpm.

Conditions for Setting the Fault Codes

The electronic control module (ECM) detects that the soot load of the aftertreatment diesel particulate filter has reached the first stage of plugging.

Action Taken When the Fault Code is Active

• The ECM will illuminate the AFTERTREATMENT dash lamp immediately after the diagnostic is set.
• The ECM will flash the AFTERTREATMENT dash lamp as the severity of the soot load increases.
• Torque output of the engine will be reduced as the soot load in the aftertreatment diesel particulate filter increases.

Conditions for Clearing the Fault Code

The ECM will turn off the AFTERTREATMENT dash lamp immediately after the soot load in the aftertreatment diesel particulate filter has dropped below the recommended limits.

Shop Talk

Verify the electronic control module (ECM) calibration is correct. Check the calibration revision history found on QuickServe® Online for applicable fixes to the calibration stored in the ECM. If necessary, recalibrate the ECM. Refer to Procedure 019-032 (ECM Calibration Code) in Section 19 in the corresponding Troubleshooting and Repair Manual for the engine being serviced.

Note: This fault code indicates that the aftertreatment diesel particulate filter requires maintenance by preforming a stationary regeneration procedure. This is a maintenance procedure only and is not covered by Cummins warranty.

Possible causes of this fault code include:

• The engine has been operating in light load operating conditions that prevent exhaust temperatures from being high enough to regenerate the aftertreatment diesel particulate filter.
• A possible engine damage that causes excessive black smoke to be generated.

The aftertreatment diesel particulate filter soot loading can be classified into four different stages. As the soot load increases, the AFTERTREATMENT lamp and the Cummins CHECK ENGINE (Amber) or STOP ENGINE (Red) lamp will operate according to the table below. The stationary regeneration procedure can be used to clear the soot from the aftertreatment diesel particulate filter in stages 1, 2, and 3. At level 4, the aftertreatment diesel particulate filter is completely plugged and must be replaced. Inadequate exhaust temperatures entering the aftertreatment system can be a cause of high soot loads in the aftertreatment diesel particulate filter. The duty cycle of the application may need to be increased in order to prevent excessive soot from accumulating in the filter.

Refer to Troubleshooting Fault Code t05-2639