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SPN 3364 FMI 13

Aftertreatment 1 DEF Quality — Out of calibration.
The component or the controller's calibration for it is not within the expected range.

What the SPN covers: Whether the fluid in the DEF tank has the right urea concentration. More on SPN 3364.

What FMI 13 usually points to: A replaced part that needs a calibration or learn procedure, wrong software, or a worn component. More on FMI 13.

Severity

MEDIUM — fix soon

Poor DEF quality causes inducement derates. Drain and refill with fresh certified DEF.

Likely causes

  1. Diluted or contaminated DEF (water, coolant, wrong fluid)
  2. Old DEF that has degraded in heat
  3. Faulty quality sensor

Checks & fixes (easiest first)

  1. Test DEF with a refractometer
  2. Drain, flush and refill with fresh DEF
  3. Inspect the tank sender for contamination

FAQ

What does SPN 3364 FMI 13 mean?

Aftertreatment 1 DEF Quality — out of calibration. The component or the controller's calibration for it is not within the expected range.

Is SPN 3364 FMI 13 serious?

Poor DEF quality causes inducement derates. Drain and refill with fresh certified DEF.

What should I check first for SPN 3364 FMI 13?

Test DEF with a refractometer; Drain, flush and refill with fresh DEF; Inspect the tank sender for contamination.