The Cummins fault code 2742 troubleshooting document is a 4-page factory diagnostic reference for the Cummins ISM and ISX CM871 (2007-09) engine platform, covering exhaust gas temperature 2 low (SPN 3249, FMI 17). This fault code sets when aftertreatment exhaust gas temperature 2 is below the normal operating range at the least severe level, because the engine cannot reach the commanded minimum exhaust temperature at the aftertreatment inlet before fuel injection. This page summarises what the manual contains so a technician can confirm it matches the code before downloading.
Official document details
| Brand | Cummins |
| Model coverage | ISM & ISX CM871 (2007-09) |
| System / group | ISM CM871 (2007-09) / DTCs |
| Circuit | ISX and ISM Aftertreatment System |
| Fault identifiers | SPN 3249 · FMI 17 |
| Source | TruckFaultCodes.com (© 2017) |
| Pages | 4 |
| File size | 0.1 MB |
| Format | |
| Language | English |
Cummins fault code 2742 overview
This fault code sets when aftertreatment exhaust gas temperature 2 is below the normal operating range at the least severe level, because the engine cannot reach the commanded minimum exhaust temperature at the aftertreatment inlet before fuel injection. Three temperature sensors monitor the diesel oxidation catalyst and diesel particulate filter. Verify the ECM calibration is correct.
The document lists possible causes including:
- A leaking exhaust system between the turbocharger and the diesel oxidation catalyst
- Excessive exhaust temperature loss between the turbocharger outlet and aftertreatment inlet
- A missing or incorrect, poorly insulated OEM downpipe
- Engine oil, coolant, or fuel contamination in the turbocharger exhaust outlet
Document table of contents
- Description
- Shop Talk
- Component Location
- Troubleshooting Steps
Applicable truck models covered
This procedure applies to Cummins ISM and ISX engines built on the CM871 (2007-09) electronic control platform, as fitted by truck makers using this Cummins driveline. The aftertreatment diesel oxidation catalyst is in the exhaust; its location varies by OEM. For wiring, connector, and CPL detail, refer to the Cummins official engine support site or the OEM service manual.
Who needs this Cummins fault code 2742 manual
Fleet technicians and workshop owners diagnosing low aftertreatment exhaust temperature on ISM or ISX CM871 engines use this reference to follow the factory step order instead of guessing at the diesel particulate filter circuit. The full PDF is available in the DiagTechPro manuals library, and a free account is required to download.
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