SPN 1761 FMI 31 is the Detroit DD-series code for a very low Diesel Exhaust Fluid (DEF) tank level (level 3), and this sheet states the tank condition, the engine reaction and the refill procedure that clears it. It is a status warning, not a wiring fault.
Official document details
| Brand | Detroit |
| Model coverage | DD13, DD15, DD16 (EPA 2007-current) |
| System / group | DEF / SCR aftertreatment |
| Fault code | SPN 1761 / FMI 31 |
| Publication no. | Not printed on sheet |
| Year / revision | Reference dated 2017 |
| Pages | 1 |
| File size | 0.2 MB |
| Format | |
| Language | English |
Document table of contents
- Fault header: SPN 1761 / FMI 31 — DEF tank level 3 condition — tank level very low
- Description and engine reaction (low-level warning)
- Refill and idle-verification procedure
- When to move to DEF level sensor diagnostics
SPN 1761 FMI 31 troubleshooting steps
This fault indicates the DEF tank level is very low. Diesel Exhaust Fluid (DEF) must be added to the tank, a minimum of one-quarter tank. After refilling, idle the engine for about five minutes to let the level reading update. If the fault does not go inactive or the dash lamp stays on after the refill and idle, the sheet directs you to OEM literature for DEF level sensor diagnostics rather than continuing to add fluid.
Applicable truck models
This warning applies to Detroit DD-series engines — DD13, DD15 and DD16 on the EPA 2007-current platform with SCR aftertreatment — and shares its SPN/FMI structure with related Series 60 DDEC VI applications. Confirm the emissions calibration (EPA07, EPA10 or GHG14) and DEF quality before acting. For engine serial-number and calibration confirmation, use the Detroit Diesel official support site.
Who needs the SPN 1761 FMI 31 manual
Drivers, dispatchers and shop technicians use this sheet to understand a DEF low-level warning, the derate it triggers and the simple refill-and-idle step that clears it before any sensor is condemned.
The full PDF is available in the DiagTechPro manuals library; a free account is required to download. Source: Detroit SPN/FMI fault-code reference (© 2017); DEF level and derate status are read with the Detroit Diesel Diagnostic Link (DDDL).
Related manuals library
