Cummins fault code 1968 is documented on this DiagTechPro library page for Cummins ISM CM871 (2007-09) engines, where it flags the Aftertreatment Exhaust Gas Temperature 2 – Data Valid but Above Normal Operational Range – Moderately Severe Level condition (PID S327, SPN 3249, FMI 0/16, Amber lamp). This 4-page PDF reproduces the manufacturer description, shop talk, component location and step-by-step troubleshooting so technicians can confirm and clear the code.
Cummins fault code 1968 overview
Cummins identifies this code as “Aftertreatment Exhaust Gas Temperature 2 – Data Valid but Above Normal Operational Range – Moderately Severe Level” on the Aftertreatment Temperature Sensors. The aftertreatment temperature sensors are used by the electronic 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.
According to the shop talk notes, possible causes include:
- A damaged fuel injector causing unburned fuel to enter the exhaust system.
- A damaged aftertreatment fuel injector.
Official document details
| Brand | Cummins |
| Model coverage | Cummins ISM CM871 (2007-09); Cummins ISX CM871 (2007-09) |
| System / Group | Aftertreatment Temperature Sensors — ISM CM871 fault codes |
| Fault code | 1968 (SPN 3249, FMI 0/16) |
| PID | S327 |
| Warning lamp | Amber |
| Source | TruckFaultCodes.com Cummins fault code reference (© 2017) |
| Pages | 4 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification (PID, SPN, FMI, lamp)
- Description
- Shop Talk
- Component Location
- Troubleshooting Steps
Applicable truck models and engines
This document applies to Cummins ISM CM871 (2007-09); Cummins ISX CM871 (2007-09) equipped diesel engines that log Fault Code 1968. Always confirm engine calibration and use a Cummins diagnostic tool such as INSITE to read live data before replacing parts. Full specifications are published on the Cummins official website.
Who needs this Cummins fault code 1968 manual
Heavy-duty truck technicians, fleet workshops and owner-operators diagnosing an electronic control module warning on ISM CM871 engines use this sheet to verify the fault before parts are replaced.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download.
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