Code Details
| Display code | SPN 1761 FMI 1 |
|---|---|
| SPN | 1761 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | Volvo |
| System | Aftertreatment — DEF supply |
| Component | DEF tank level sensor / DEF supply module |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-12 |
Plain-English Meaning
The Volvo D13 requires diesel exhaust fluid in the SCR catalyst to meet emissions standards. When the DEF level sensor detects that the tank has dropped below the low-level calibration point, the engine control system begins an inducement sequence. The driver will see a warning lamp and may receive a message through the Volvo display. Adding DEF and resetting the fault with VCADS Pro or Tech Tool returns the truck to normal operation.
SPN 1761 is Aftertreatment 1 DEF Tank Level in the J1939 protocol, with FMI 1 indicating below-normal range. On Volvo D13 engines used in VNL, VNR, and VHD models, the DEF level sensor is part of the aftertreatment supply module. The engine ECU and aftertreatment control module together manage the inducement sequence when SPN 1761 FMI 1 is active. VCADS Pro (Vehicle Computer Aided Diagnostics) and the Volvo Tech Tool provide access to live DEF level sensor readings, inducement stage data, and the inducement reset function.
Common Symptoms
- Amber SCR or DEF warning lamp on the Volvo instrument cluster
- DEF level or aftertreatment system warning on the Volvo driver information display
- Progressive torque and power reduction if the inducement advances past the initial warning stage
- Inducement stage and accumulated distance readable in VCADS Pro or connected fleet management systems
- Potential road speed limitation in the final inducement stage until the DEF level is restored
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- DEF tank depleted below the calibrated low-level threshold
- DEF level sensor or integrated sensor module failed
- Wiring harness or connector fault on the DEF level sensor circuit
- DEF filler opening seal degraded, allowing gradual leakage
- DEF removed from the tank during service without being replaced before the truck left the shop
First Checks
- Verify the actual DEF level using the Volvo instrument cluster DEF gauge or by physically checking the tank
- Add fresh DEF if the level is confirmed low and observe whether the warning clears after a short drive cycle
- Connect VCADS Pro or Volvo Tech Tool and navigate to the aftertreatment section to read the DEF level sensor output and compare it with the known physical level
- Check for companion fault codes such as SPN 3361 or SPN 3480 that would indicate a supply or dosing system problem alongside the level fault
- Inspect the DEF module wiring and connector for moisture, corrosion, or mechanical damage if the tank is confirmed full but the fault remains active
- Perform the inducement reset using VCADS Pro after the DEF level is verified as acceptable
Can I Keep Driving?
The D13 can continue operating with SPN 1761 FMI 1 active at the initial warning stage, but the inducement will escalate over accumulated miles. Torque and speed restrictions follow. Refilling the DEF tank and clearing the inducement with VCADS Pro or Tech Tool restores full engine performance.
Related Codes
Related Lookup Pages
Sources
- Volvo Trucks Tech Info Public Resources Volvo Trucks North America · oem · accessed 2026-06-11 · confidence medium
Source: Volvo Trucks North America, Volvo Trucks Tech Info Public Resources. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - SAE J1939 Standards Collection SAE International · official · accessed 2026-05-05 · confidence medium
Source: SAE International, SAE J1939 Standards Collection. This page paraphrases factual fields only and is not a substitute for the original document.
Open source
FAQ
How does the Volvo D13 inducement sequence work for SPN 1761 FMI 1?
The Volvo D13 uses a distance-based inducement sequence that progresses through stages as the truck accumulates mileage with the low DEF condition active. Each stage applies increasing restrictions, from a warning lamp to torque reduction to a road speed cap. VCADS Pro or the Volvo Tech Tool displays the current inducement stage and the accumulated distance, letting the technician assess urgency.
Is the DEF level sensor on the Volvo D13 integrated with the DEF pump module?
On many Volvo D13 applications, the DEF supply module integrates the pump, level sensor, quality sensor, and heater into a single assembly. A failed level sensor in this configuration typically requires replacing the entire module. VCADS Pro can test individual sensor outputs within the module to confirm which component has failed before recommending a replacement.
Can a very cold start cause a false SPN 1761 FMI 1 on the Volvo D13?
In extreme cold, partially frozen DEF can interfere with the level sensor operation before the DEF heater has fully thawed the tank. If this fault appears only on cold starts and clears as the truck warms up, the condition may be related to the DEF heating system or to a DEF level that is borderline low and appears even lower when the fluid is partially frozen. A refill and inspection of the DEF heater circuit is appropriate in that case.