The ISM code 122 DTCs manual is a 5-page PDF that documents fault code 122, the intake manifold 1 pressure sensor circuit fault set for voltage above normal or shorted to high source. It explains how the ECM supplies 5 volts to the intake manifold pressure sensor and reads a signal that changes with boost pressure in the intake manifold. The procedure is credited to TruckFaultCodes.com and covers the circuit description, component location and full troubleshooting steps.
Official document details
| Brand | Cummins |
| Model coverage | Cummins ISM CM871 and ISX CM871 (2007-09) engines |
| System / group | ISM CM871 (2007-09) / DTCs |
| Fault code | 122 (PID P102, SPN 102, FMI 3) |
| Pages | 5 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code 122 description
- Circuit description and ECM operation
- Component location
- Shop talk and possible causes
- Step-by-step troubleshooting flow
Applicable truck models
This diagnostic applies to Cummins ISM CM871 and ISX CM871 (2007-09) engines. The intake manifold pressure sensor is located in the air intake horn and shares supply and return wires with other sensors, so a single fault can trigger multiple codes. Possible causes include an open return circuit in the engine harness, connectors or sensor, or a signal wire shorted high. For engine data and authorised service, visit the Cummins official website.
Who needs this ISM code 122 DTCs manual
Heavy-duty diesel technicians, fleet workshops and owner-operators reach for this manual when fault code 122 is logged. It provides the key-on checks, connector inspections and voltage measurements needed to isolate the sensor, harness or ECM before replacing parts.
Download the code 122 DTCs PDF
The complete procedure, wiring detail and step tables are available in the DiagTechPro manuals library; a free account is required to download the PDF. Keep it alongside the related ISM CM871 fault-code sheets listed below.
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