Code Details
| Display code | SPN 3364 FMI 1 |
|---|---|
| SPN | 3364 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | PACCAR |
| System | Aftertreatment �?DEF system |
| Component | DEF quality / concentration sensor |
| Source address | Unknown or not applicable |
| Severity | medium |
| Review status | source backed |
| Source confidence | medium |
| Last reviewed | 2026-06-11 |
Plain-English Meaning
The PACCAR MX-13's SCR system requires DEF with approximately 32.5% urea concentration to reduce NOx emissions. When the quality sensor reads below that level �?from wrong fluid, dilution, or degraded DEF �?the engine ECU logs this code and begins the inducement countdown that eventually derates the engine if left unresolved.
SPN 3364 is Aftertreatment 1 DEF Concentration in J1939. FMI 1 indicates a valid reading below the normal range. The PACCAR MX-13 uses a proprietary engine control system that integrates with PACCAR's diagnostic software (DAVIE or PDIAG). When DEF quality falls below the calibrated minimum, the ECU activates the SCR inducement logic. The MX-13 shares its aftertreatment design architecture with European DAF engines from which it is derived, and the same progressive inducement sequence applies: warning, then torque derate, then speed limit.
Common Symptoms
- Amber check engine or DEF warning lamp active
- DEF quality warning on the Kenworth or Peterbilt dash display
- Inducement distance counter in the instrument cluster or telematics
- No immediate power loss at initial fault set
Possible Causes
Possible causes may include the items below. The list is not a parts diagnosis.
- DEF tank filled with water or wrong fluid
- DEF diluted by water ingestion through a leaking filler cap
- DEF aged or heat-degraded below minimum urea concentration
- DEF quality sensor fault
- Wiring fault at the quality sensor harness connector
First Checks
- Sample DEF from the tank and inspect for cloudiness or discoloration
- Connect PACCAR diagnostic software and check active codes and inducement counter distance
- Monitor DEF quality sensor live data
- Inspect DEF filler cap and tank for damage or contamination sources
- Check the quality sensor wiring harness connector if fluid quality is good but sensor still reads low
Can I Keep Driving?
The MX-13 can continue operating in the warning stage, but the inducement timer is running. At highway speeds, the distance accumulates quickly. Resolve the DEF quality issue and reset the counter via PACCAR diagnostic software before any long-haul departures.
Related Codes
Related Lookup Pages
Sources
- PACCAR / Kenworth / Peterbilt Service Support — MX Engine Resources PACCAR Inc. · oem · accessed 2026-06-11 · confidence medium
Source: PACCAR Inc., PACCAR / Kenworth / Peterbilt Service Support — MX Engine Resources. This page paraphrases factual fields only and is not a substitute for the original document.
Open source - PACCAR Engine Technical Services PACCAR Inc. · oem · accessed 2026-06-10 · confidence medium
Source: PACCAR Inc., PACCAR Engine Technical Services. 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
What diagnostic tool is used to reset the DEF inducement counter on a PACCAR MX-13?
PACCAR DAVIE (Diagnostic And Vehicle Information Equipment) or PDIAG is the primary diagnostic software for MX-13 engines. After correcting the DEF quality issue, the inducement counter can be reset and fault codes cleared using DAVIE. Some Kenworth and Peterbilt dealers also have access through TruckTech+ or proprietary service portals.
Is the PACCAR MX-13 DEF system similar to other heavy-duty engines?
The MX-13 uses an SCR-based aftertreatment system that follows the same general J1939 fault code structure as other heavy-duty engines. However, the specific control logic, inducement thresholds, and service procedures are calibrated for the MX-13 platform and should be followed using PACCAR-specific documentation and diagnostic tools.
Can SPN 3364 FMI 1 on the PACCAR MX-13 be caused by extreme cold temperatures affecting DEF?
DEF freezes at approximately -11°C (12°F). Modern DEF systems have tank heaters to thaw frozen DEF, and frozen DEF does not permanently degrade the fluid. However, if the tank heater fails or the system is used in very cold conditions before the DEF has thawed, the quality sensor may read incorrectly until the DEF returns to liquid form.