This one-page style reference documents Detroit fault code SPN 4358 FMI 4, the diesel exhaust fluid (DEF) metering unit doser heater circuit circuit failed low condition on DD Series (EPA 2007-current) aftertreatment systems. It walks the technician through inspecting the harness for bent, spread or corroded pins, disconnecting the ACM 120-pin connector, and measuring resistance to separate a wiring fault from a failed component. The procedure is sourced from the TruckFaultCodes.com Detroit fault-code library (© 2017) and mirrors the checks in Detroit Power Service Literature.
SPN 4358 FMI 4 document details
| Brand | Detroit |
|---|---|
| Model coverage | DD Series (EPA 2007-current) diesel engines |
| System / group | Diesel Exhaust Fluid (DEF) Metering Unit Doser Heater Circuit — DTCs |
| Diagnostic trouble code | 4358 / 4 (circuit failed low) |
| Source / revision | TruckFaultCodes.com, © 2017 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault code identification and affected system
- Fault description and dash-lamp reaction
- Step-by-step troubleshooting procedure
- Harness connector and terminal pin inspection
- Resistance measurement and short-circuit checks
- Wiring repair and component replacement guidance
Applicable truck models covered
This procedure applies to Detroit DD Series engines built to EPA 2007 and later emissions standards, and it is cross-referenced to Series 60 (DDEC VI, EPA 2007) applications that share the same ACM aftertreatment control module. This particular sheet documents the EPA10 calibration of code 4358 / 4. Diagnosis begins by connecting a diesel diagnostic tool and confirming the fault is active before any wiring is disturbed. For engine identification, emissions family and warranty coverage, consult the official Demand Detroit website.
Who needs this SPN 4358 FMI 4 manual
Diesel technicians, fleet maintenance staff and independent workshop owners who need a fast, accurate reference for this DEF doser heater circuit failed low will save diagnostic time with this sheet. It states the exact connector pins, resistance windows and repair-versus-replace decisions instead of guesswork, which is why it is one of the most requested pages in the DiagTechPro fault-code collection.
The complete PDF, including the resistance chart and pin values referenced in the final steps, is available in the DiagTechPro manuals library — a free account is required to download it.
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