This Cummins 1657 misfire troubleshooting document provides the complete diagnostic procedure for Fault Code 1657 — Engine Misfire Cylinder 4, Condition Exists. It covers circuit description, conditions for setting and clearing the code, shop talk guidance, and a guided step-by-step troubleshooting tree for CM2250-controlled engines.
Official Cummins 1657 misfire troubleshooting document details
| Brand | Cummins |
| Model coverage | ISX15 CM2250, ISX11.9 CM2250, QSL9 CM2250, QSB6.7 CM2250 |
| System / Group | ISB6.7 CM2250 (2010-12) / Diagnostic Trouble Codes (DTCs) |
| Publication no. | — |
| Year / Revision | Last modified 20-Jul-2010 |
| Pages | 7 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Overview — Circuit Description, Component Location
- Conditions for Running the Diagnostics
- Conditions for Setting the Fault Codes (SPN 1326, FMI 11/31)
- Action Taken When the Fault Code is Active
- Conditions for Clearing the Fault Code
- Shop Talk — Causes of Cylinder Misfire
- Associated Procedures Table (Procedure 006-026 Injector, Procedure 019-032 ECM Calibration Code)
- Guided Step 1 — Check the Fault Codes (1A: Read fault codes, 1B: Check for cylinder misfire)
- Guided Step 2 — Perform Diagnostic Tests (2A: Cylinder cutout test)
- Guided Step 3 — Check if an ECM Calibration Update is Available (3A: Compare revision, 3B: Disable the fault code)
Applicable truck models
This document applies to Cummins engines equipped with CM2250 electronic control modules, specifically the ISX15 CM2250 (Bulletin 4022250), ISX11.9 CM2250 (Bulletin 2883445), QSL9 CM2250 (Bulletin 4022256), and QSB6.7 CM2250 (Bulletin 4022255). The ECM algorithm monitors engine speed contribution at idle for cylinder 4, with the diagnostic running continuously when engine coolant temperature exceeds 71°C (160°F). An amber CHECK ENGINE lamp illuminates when the fault is active. The procedure requires INSITE™ electronic service tool for fault code reading, cylinder cutout testing, and ECM calibration verification. Causes addressed include valve lash out of specification, cylinder or valve malfunction, cylinder head or gasket damage, extreme camshaft wear, injector sealing washer issues, injector malfunction, and mistimed air compressor. For official technical resources, visit Cummins official website.
Who needs this Cummins 1657 misfire troubleshooting manual
Diesel mechanics and workshop owners diagnosing low power, rough idle, or misfire complaints on CM2250-equipped Cummins engines need this procedure. It provides the exact diagnostic sequence — from reading fault codes through the cylinder cutout test to ECM calibration verification — required to isolate and resolve a cylinder 4 misfire condition.
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