SPN 168 FMI 18 is a Detroit DD Series diagnostic trouble code, and this 3-page PDF fault-code sheet documents the “Battery Voltage LOW” condition together with its monitored parameter, enabling conditions and factory troubleshooting steps. The reference is published on TruckFaultCodes.com (Copyright © 2017) and mirrors the Detroit™ DiagnosticLink flow used by dealer technicians. Use it to confirm the code before you open the harness.
SPN 168 FMI 18 document details
| Brand | Detroit (Detroit Diesel) |
|---|---|
| Model coverage | Detroit DD Series engines — DD13, DD15 and DD16 (EPA 2007 to current); also referenced for Series 60 DDEC VI |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Fault code | SPN 168, FMI 18 — GHG14 |
| Fault description | Battery Voltage LOW |
| Source / Revision | TruckFaultCodes.com, Copyright © 2017 |
| Pages | 3 |
| File size | 0.3 MB |
| Format | |
| Language | English |
Fault code description and checks
This Detroit fault code sheet identifies the battery voltage low fault reported by the Motor Control Module (MCM) as SPN 168, FMI 18. The numbered troubleshooting procedure walks the technician through inspecting the sensor and 120-pin MCM connector, measuring circuit resistance, checking voltage drop across power and ground wires before any part is replaced.
Document table of contents
- Fault code header — SPN and FMI identifiers
- Step-by-step troubleshooting procedure
Applicable truck models
This diagnostic covers Detroit DD13, DD15 and DD16 engines built to EPA 2007 and later emissions standards, as fitted to Freightliner Cascadia and Western Star highway tractors, and it is also cross-referenced for Series 60 engines running DDEC VI. Confirm engine serial and calibration coverage against the current data on Detroit’s official Detroit engine platform website before ordering parts.
Who needs this SPN 168 FMI 18 manual
Fleet technicians, mobile diesel mechanics and workshop owners who pull this code on DiagnosticLink use the sheet to separate a genuine sensor or wiring fault from a false trigger, saving guesswork and unnecessary parts. It is written for hands-on repair, not classroom study.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download it.
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