The SPN 97 FMI 31 document is a Detroit DD Series diagnostic trouble code guide covering the water-in-fuel (WIF) sensor defect condition and its step-by-step troubleshooting. This 4-page PDF is compiled from the TruckFaultCodes.com Detroit fault codes reference (© 2017) for the DD Series (EPA 2007-Current) / DTCs set. It is written for workshop diagnostics rather than general reading.
Official document details
| Brand | Detroit |
| Model coverage | Detroit DD Series (EPA 2007-Current); Detroit Series 60 (DDEC VI – EPA 2007) |
| System / Group | DD Series (EPA 2007-Current) / DTCs |
| Diagnostic trouble code | SPN 97/FMI 31 — Water-In-Fuel Sensor Defect |
| Publication no. | Not stated (TruckFaultCodes.com DTC reference) |
| Year / Revision | © 2017 |
| Pages | 4 |
| File size | 0.3 MB |
| Format | |
| Language | English |
SPN 97 FMI 31 document sections
- Fault code identification: SPN 97/FMI 31 — WIF sensor defect
- Two-filter versus three-filter WIF circuitry (KM63 GEN2 differences)
- Clearing the code and the two-minute engine run test
- Inspecting the WIF harness connector for damage and water intrusion
- Power and ground checks at the WIF sensor harness connector
Applicable truck models covered
The SPN 97 FMI 31 fault applies to the models below. This procedure covers Detroit DD Series (EPA 2007-Current); Detroit Series 60 (DDEC VI – EPA 2007) engines equipped with the Motor Control Module. The steps reference the systems named in the extract only — water-in-fuel sensor components, harness connectors and, where present, the MCM 120-pin connector. Confirm engine and emissions configuration against the vehicle build before ordering parts; verify current procedures on the Detroit Diesel official site.
Who needs this 97 FMI 31 manual
This reference suits fuel-system technicians and workshop owners servicing water-in-fuel warnings and WIF sensor circuits on Detroit engines. Every troubleshooting step and decision branch from the original PDF is preserved so the on-vehicle diagnosis can be followed in sequence. Use it alongside a Detroit-compatible scan tool such as DDDL or DDRS.
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