Detroit DD16 GHG14 (2014-16) Fault Code: SPN 4331 FMI 18 (ACM) DEF Dosing Quantity Low

Posted by PerDiezel Solutions on April 22, 2026

NOTE: The fault indicates that the DEF pump speed is high compared to DEF quantity delivered. The CEL lamp will remain on until the fault is resolved.

NOTE: If code 3364-xx present, fix that first.

PROBABLE CAUSES:
1. Check all DEF supply lines for damage or leaks.
2. DEF tank is contaminated with gas, diesel, water, etc…
3. Doser valve failure.
4. DEF pump.
5. DEF pump connection/harness.

WARNING!