CM871 and CM876 Electronic Control Systems, ISX and ISM Engines – FAULT CODE 2728

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Overview

ISX and ISM – Aftertreatment System SMALL | MEDIUM | LARGE

Circuit Description

The aftertreatment system is monitored by three temperature sensors that are located in the exhaust system. The aftertreatment diesel oxidation catalyst inlet temperature sensor is located after the turbocharger outlet at the inlet of the aftertreatment system. The aftertreatment diesel particulate filter inlet temperature sensor is located between the aftertreatment diesel oxidation catalyst and the aftertreatment diesel particulate filter. The aftertreatment diesel particulate filter outlet temperature sensor is located after the aftertreatment diesel particulate filter. The temperature sensors around the aftertreatment diesel oxidation catalyst are used to monitor the temperature differential across the catalyst during active regeneration of the aftertreatment system.

Component Location

The aftertreatment diesel oxidation catalyst is located in the exhaust system. The location of the catalyst can vary, depending on the original equipment manufacturer (OEM). Refer to the OEM service manual.

Conditions for Running the Diagnostics

The diagnostic runs continuously when the engine is running and an active regeneration of the aftertreatment system is occurring.

Conditions for Setting the Fault Codes

The aftertreatment system has detected that an active regeneration event has occurred longer than a calibratible time and that the aftertreatment temperatures have not reached the minimum temperature for a complete regeneration of the diesel particulate filter to occur.

Action Taken When the Fault Code is Active

• The fault code is set active immediately when the diagnostic runs and fails.
• The aftertreatment diesel particulate filter lamp (if equipped) will become illuminated after the diagnostic runs and fails three times.

Conditions for Clearing the Fault Code

A regeneration event, either stationary or mobile, must be performed before this fault code will clear.

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.

The aftertreatment system will try to meet target temperatures at the outlet of the diesel oxidation catalyst during a regeneration event. This fault code is activated when the control system detects that the aftertreatment fuel injector is injecting excessive fuel into the exhaust system trying to meet the target temperatures at the diesel oxidation catalyst outlet temperature sensor.

Possible causes of this fault code include:

• Soot plugging the front face of the aftertreatment diesel oxidation catalyst
• Engine oil or fuel contamination of the aftertreatment diesel oxidation catalyst
• A cracked or contaminated aftertreatment diesel oxidation catalyst
• A malfunction in the aftertreatment fuel injection system
• A leaking exhaust system between the turbocharger and the aftertreatment diesel oxidation catalyst
• The duty cycle of the vehicle is not high enough to provide adequate exhaust temperatures for a complete regeneration event.

Refer to Troubleshooting Fault Code t05-2728