SPN 3364 — Aftertreatment 1 DEF Quality
System: Aftertreatment / DEF
Whether the fluid in the DEF tank has the right urea concentration.
Can I keep running it?
MEDIUM — fix soon
Poor DEF quality causes inducement derates. Drain and refill with fresh certified DEF.
Likely causes
- Diluted or contaminated DEF (water, coolant, wrong fluid)
- Old DEF that has degraded in heat
- Faulty quality sensor
Checks & fixes (easiest first)
- Test DEF with a refractometer
- Drain, flush and refill with fresh DEF
- Inspect the tank sender for contamination
Common FMIs with SPN 3364
- SPN 3364 FMI 1Value too low (most severe)
- SPN 3364 FMI 2Data erratic, intermittent, or incorrect
- SPN 3364 FMI 13Out of calibration
- SPN 3364 FMI 18Value too low (moderately severe)
Related codes
- SPN 1761Aftertreatment 1 DEF Tank Volume
- SPN 4364Aftertreatment 1 SCR Conversion Efficiency
- SPN 5246Aftertreatment SCR Operator Inducement Severity
FAQ
What does SPN 3364 mean?
SPN 3364 is Aftertreatment 1 DEF Quality. Whether the fluid in the DEF tank has the right urea concentration.
Can I keep running with SPN 3364?
Poor DEF quality causes inducement derates. Drain and refill with fresh certified DEF.
What causes SPN 3364?
Diluted or contaminated DEF (water, coolant, wrong fluid); Old DEF that has degraded in heat; Faulty quality sensor.