Code Details
| Display code | SPN 3364 FMI 1 |
|---|---|
| SPN | 3364 |
| FMI | 1 |
| OEM code | None listed |
| Manufacturer | Ford |
| 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 Ford 6.7L Power Stroke uses a Selective Catalytic Reduction system that requires DEF with approximately 32.5% urea concentration. When the quality sensor detects a lower concentration �?from wrong fluid, dilution, or aging �?the PCM logs this code and begins the inducement countdown that eventually derates the engine. This engine is found in F-250 through F-550 Super Duty trucks and commercial chassis applications.
SPN 3364 is Aftertreatment 1 DEF Concentration in J1939. FMI 1 indicates a valid reading below the normal range. The Ford 6.7L Power Stroke uses the Ford Powertrain Control Module with an integrated Selective Catalytic Reduction control strategy. Ford IDS (Integrated Diagnostic System) or FDRS (Ford Diagnostic and Repair System) is used to access DEF quality sensor data, inducement counter distance, and companion aftertreatment codes. Ford's inducement system follows the EPA-mandated progressive derate sequence.
Common Symptoms
- Wrench indicator lamp or check engine lamp active
- DEF quality warning message on the Ford instrument cluster display
- Inducement countdown visible in the message center or fleet 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, windshield washer fluid, or other 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
First Checks
- Sample DEF from the tank and inspect for cloudiness or unusual odor
- Connect Ford IDS or FDRS and check active codes, DEF quality sensor live data, and inducement counter
- Inspect DEF filler cap and tank for damage or contamination
- Check sensor wiring if DEF quality is good but sensor reads low
Can I Keep Driving?
The Ford 6.7 Power Stroke can continue operating in the warning stage, but the inducement timer is running. On commercial chassis applications and fleet vehicles, address this before any long run to avoid an in-service derate.
Related Codes
Related Lookup Pages
Sources
- Ford Trucks Service Support Public Resources Ford Motor Company · oem · accessed 2026-06-11 · confidence medium
Source: Ford Motor Company, Ford Trucks Service Support 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
What Ford diagnostic tool is used to reset the DEF inducement counter on a 6.7 Power Stroke?
Ford IDS (Integrated Diagnostic System) or FDRS (Ford Diagnostic and Repair System) is used by Ford dealers and authorized shops. After correcting the DEF quality issue and confirming the sensor reads within range, the fault codes and inducement counter are reset using these tools. Some code readers with Ford-specific coverage may also clear codes, but full inducement counter reset typically requires the dealer-level tools.
Is the Ford 6.7 Power Stroke DEF system the same as used in commercial trucks like the F-650?
The 6.7L Power Stroke engine family is used across multiple Ford platforms from the F-250 Super Duty through the F-650/750 commercial trucks. The aftertreatment system design is shared across these applications, but calibration and component sizing may differ. Service procedures are similar, and Ford IDS covers all of these applications.
Can SPN 3364 FMI 1 cause the Ford 6.7 Power Stroke to shut down completely?
SPN 3364 FMI 1 triggers an inducement sequence rather than an immediate shutdown. The sequence escalates from a warning through progressive derates �?reduced torque, then reduced vehicle speed �?over the inducement distance. A complete shutdown is not the typical outcome of DEF quality faults alone, though allowing the fault to escalate to the maximum derate stage severely limits the vehicle's operating capability.