CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2879 (ISX)

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Overview

ISX and ISM – Aftertreatment Fuel Injector System SMALL | MEDIUM | LARGE

Circuit Description

This fault code checks for system errors in the aftertreatment fuel injection system. This diagnostic can detect fuel leaks in the system as well as failures of the aftertreatment fuel injector, aftertreatment fuel shutoff valve, and aftertreatment fuel drain valve.

Every time the engine is started, a diagnostic test on the system is performed. The aftertreatment fuel drain valve opens and relieves fuel pressure in the line. The aftertreatment fuel pressure sensor must be reading atmospheric pressure at this point in the test. The aftertreatment fuel drain valve closes and the aftertreatment fuel shutoff valve opens. This pressurizes the aftertreatment fuel system to gear pump operating pressure. The diagnostic then checks to make sure the aftertreatment fuel pressure sensor is reading gear pump operating pressure. The aftertreatment fuel shutoff valve then closes and traps the fuel between the aftertreatment fuel shutoff valve and the aftertreatment fuel injector. The diagnostic checks to make sure the system maintains fuel pressure. The aftertreatment fuel injector then briefly opens and relieves some of the fuel pressure trapped between the aftertreatment fuel shutoff valve and the aftertreatment fuel injector. The aftertreatment fuel drain valve then opens and relieves the remaining pressure in the system.

Component Location

The aftertreatment fuel injector is installed in the exhaust system in the turbocharger outlet flange. The aftertreatment fuel pressure sensor, aftertreatment fuel shutoff valve, and aftertreatment fuel drain valve are installed in the shutoff valve manifold. Refer to Procedure 100-002 in Section E.

Conditions for Running the Diagnostics

This diagnostic runs:

• During the first 5 minutes of engine operation
• Prior to injecting fuel for an active regeneration, but only if greater than 2 hours have elapsed since the previous regeneration event or key-on
• After an active regeneration.

Conditions for Setting the Fault Codes

The electronic control module (ECM) detects an external fuel leak in the aftertreatment fuel system, internal fuel leakage past the aftertreatment fuel drain valve, or an aftertreatment fuel injector that may be leaking fuel into the exhaust system.

Action Taken When the Fault Code is Active

• The ECM will illuminate the amber CHECK ENGINE lamp immediately after the diagnostic runs and fails.
• Active regeneration of the aftertreatment diesel particulate filter will be disabled.

Conditions for Clearing the Fault Code

The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.

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, calibrate the ECM. Refer to Procedure 019-032 in Section 19.

Possible causes of this fault code include:

• Internal or external leak in the aftertreatment fuel drain valve
• Internal or external leak in the aftertreatment fuel injector
• Loose fittings in the aftertreatment fuel system
• External fuel leaks in the aftertreatment fuel system
• Third-party aftertreatment fuel shutoff valve manifold
• Fuel filter plugged.

Refer to Troubleshooting Fault Code t05-2879