Cummins fault code 485 is a red-lamp diagnostic trouble code for the Cummins ISM CM570 (1999-02) engine platform, documented in this 2-page troubleshooting PDF covering the fuel system overfueling. The manual gives the circuit description, component notes and the full step-by-step test sequence a technician follows to diagnose and clear the fault.
Official document details
| Brand | Cummins |
|---|---|
| Model coverage | ISM CM570, ISX CM570 and Signature CM570 (1999-02) |
| System / Group | ISM CM570 (1999-02) / DTCs |
| Fault code / DTC | 485 |
| Identifiers | PID P129 · SPN 1349 · FMI 0/16 |
| Warning lamp | RED |
| Pages | 2 |
| File size | 0.2 MB |
| Format | |
| Language | English |
| Source | TruckFaultCodes.com fault code library, Copyright 2017 |
Document table of contents
- Circuit Description
- Component Location
- Shop Talk
- Troubleshooting Steps
- Fault Code Verification and Reset
Cummins fault code 485 circuit description
The electronic control module (ECM) supplies voltage to open the fueling actuators for a short length of time. This allows a short pulse of fuel to flow to the injector. The injector then injects this fuel into the cylinder for combustion. The ECM measures the amount of fuel metered into the injector by using the rear rail pressure sensor. If the amount of fuel is above what the ECM expected, the fault code is activated. The ISM CM570 diagnostics in this file are indexed as PID P129, SPN 1349 and FMI 0/16, so it slots directly into the wider set of ISM CM570 fault codes on the platform.
Applicable truck models and engines
The procedure applies to Cummins ISM, ISX and Signature engines built on the CM570 (1999-02) electronic control module, fitted to a wide range of Class 7 and Class 8 on-highway trucks. Because component locations vary by chassis, the document repeatedly directs the technician to the OEM troubleshooting and repair manual for exact positions. Verify engine and calibration data against the official Cummins engine support resources before ordering parts.
Who needs this Cummins fault code 485 manual
Heavy-duty truck technicians, fleet maintenance teams and independent workshop owners use this reference when a red warning lamp and this DTC appear on the diagnostic tool, or when validating a repair on an ISM CM570 engine.
The complete PDF is available in the DiagTechPro manuals library; a free account is required to download the full document.
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