Code Details
| Display code | SPN 3364 FMI 1 |
|---|---|
| SPN | 3364 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | Volvo |
| System | Aftertreatment �?DEF / SCR system |
| Component | DEF quality sensor / SCR system |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The Volvo D16 SCR system requires DEF with 32.5% urea concentration to convert exhaust NOx into nitrogen and water. When the quality sensor detects too-diluted or contaminated fluid, it initiates an inducement sequence. Left unresolved, this results in a progressive power derate governed by federal emissions regulations. On Volvo VNL and VHD trucks with the D16 engine, the DEF quality sensor and dosing system are managed by the ACM (Aftertreatment Control Module). VCADS Pro provides DEF quality sensor readings, dosing system status, and SCR catalyst efficiency data in a single aftertreatment diagnostic menu. The D16, being a larger displacement engine with higher NOx production, requires accurate DEF dosing to maintain SCR efficiency. A dosing pump that delivers slightly below the commanded rate can trigger SPN 3364 FMI 1 even when the DEF itself is within specification.
SPN 3364 is Aftertreatment 1 DEF Concentration. FMI 1 indicates the measured value is valid and below the minimum threshold. On Volvo D16 engines (EMS3 control), the DEF quality sensor is integrated with the DEF level sensor module in the tank. Volvo VCADS Pro displays the quality sensor value and can confirm whether the reading reflects actual poor-quality DEF or a sensor fault.
Common Symptoms
- DEF quality warning on the Volvo instrument cluster
- SCR inducement countdown visible in VCADS Pro
- No immediate power reduction at first detection
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- Non-compliant DEF with urea concentration below 32.5%
- Water or another fluid inadvertently added to the DEF tank
- Faulty DEF quality sensor reading low on good DEF
- Residual contamination from a previous tank fill
First Checks
- Drain the DEF tank and refill with ISO 22241 certified DEF from a trusted source
- Connect Volvo VCADS Pro and monitor DEF quality sensor value after refilling
- If the reading does not normalize after a confirmed-quality fill, investigate sensor function via VCADS Pro
- Rinse the tank with a small quantity of clean DEF before the main fill if suspected contamination was severe
- Connect VCADS Pro and compare DEF quality sensor reading to the specification threshold
- Check the DEF dosing pump commanded rate versus actual output in VCADS Pro live data
Can I Keep Driving?
The truck can continue operating immediately after detection, but the inducement sequence is underway. Resolve DEF quality before the escalation reaches the derate stage.
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 - Volvo Trucks / Mack Trucks Technical Support Volvo Trucks North America / Mack Trucks Inc. · oem · accessed 2026-06-10 · confidence medium
Source: Volvo Trucks North America / Mack Trucks Inc., Volvo Trucks / Mack Trucks Technical Support. 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 is the Volvo D16 different from the D13 in terms of DEF system design?
The Volvo D16 is a larger displacement (16L) six-cylinder engine used in extreme-duty applications. The DEF system architecture is the same as the D13 �?using the same EMS3 control, VCADS Pro diagnostics, and similar tank and dosing module hardware. The primary difference is the aftertreatment sizing to match the D16's higher output.
Will SPN 3364 FMI 1 clear automatically after refilling the DEF tank with quality fluid on the Volvo D16?
Yes. After refilling with compliant DEF, the quality sensor evaluates the new fluid over a drive cycle and the fault becomes inactive when the concentration returns to the acceptable range. VCADS Pro can monitor the re-evaluation and confirm the fault has cleared.
What applications typically use the Volvo D16 engine?
The Volvo D16 is targeted at high-horsepower applications including heavy haul, construction, and vocational work where maximum torque is required. It is available in Volvo FH and FM trucks in markets where these applications are common. The D16 shares its aftertreatment and emissions architecture with the D13.