This 8-page PDF is the official Cummins Fault Code 3727 troubleshooting guide for the High Pressure Common Rail Fuel Pressure Relief Valve condition described as “Mechanical System Not Responding or Out of Adjustment.” It covers diagnostic steps, fault code conditions, associated service procedures, and ECM calibration checks for CM2250-controlled engines. The document is essential for diagnosing low power or power interruption caused by the fuel rail relief valve opening at lower-than-expected pressure.
Official Cummins Fault Code 3727 document details
| Brand | Cummins |
| Model coverage | ISB6.7 CM2250, ISC8.3 CM2250, ISL9 CM2250, ISX11.9 CM2250, ISX15 CM2250, QSB6.7 CM2250, QSL9 CM2250 |
| System / Group | DTCs — High Pressure Common Rail Fuel System |
| Publication no. | Not specified |
| Year / Revision | Last modified 24-Nov-2010 (overview) / 21-Sep-2010 (troubleshooting) |
| Pages | 8 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Overview — Fault Code 3727 (PID S254, SPN 5571, FMI 7)
- Circuit Description
- Component Location
- Conditions for Running the Diagnostics
- Conditions for Setting the Fault Codes
- Action Taken When the Fault Code is Active
- Conditions for Clearing the Fault Code
- Shop Talk
- Associated Procedures Table (Procedure 005-236, 006-061, 019-032)
- Troubleshooting Steps — Guided Step 1: Read the Fault Codes
- Troubleshooting Steps — Guided Step 2: Check High Pressure Fuel System / Injector Return Flow
- Troubleshooting Steps — Guided Step 3: Check ECM Calibration and Clear Fault Codes
Applicable truck models
This document applies to all Cummins CM2250-platform engines: ISB6.7, ISC8.3, ISL9, QSB6.7, QSL9, ISX11.9, and ISX15. These engines are found in medium- and heavy-duty trucks from manufacturers such as Kenworth, Peterbilt, Freightliner, and International, as well as industrial and off-highway equipment. The primary catalog group is ISB6.7 CM2250 (2010–2012) DTCs. Associated bulletin numbers referenced include 4022254, 4022255, 4022256, 4022257, 4022250, and 2883445. For official engine documentation and service tool support, visit Cummins official website.
Who needs this Cummins Fault Code 3727 manual
Diesel mechanics and workshop owners dealing with low power complaints, intermittent power loss, or an active/inactive DTC 3727 on any CM2250 engine need this guide. It walks through injector return flow testing, high-pressure connector leak isolation, relief valve replacement (Procedure 006-061), Fuel System Diagnostic (Procedure 005-236), and ECM calibration verification (Procedure 019-032) using the INSITE™ electronic service tool.
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