Detroit DD13 EPA07 (2007-09) Fault Code: SPN 3250 FMI 4 (MCM) Diesel Oxidation Catalyst Outlet Temperature Circuit Failed Low

Posted by PerDiezel Solutions on March 8, 2026

NOTE: If any other codes are active, fix those first.

PROBABLE CAUSES:
1. Inspect all connectors upstream of the MCM (DOC outlet temperature, ATD harness 10-pin connector, VIH 31-pin connector, and ECM 120-pin connector).
2. DOC outlet temperature sensor.
3. DPF inlet pressure sensor.
4. DPF inlet pressure sensor connector/harness.
5. DPF outlet pressure sensor.
6. DPF outlet pressure sensor connector/harness.
7. DPF is contaminated with oil or coolant.
8. DOC failure.
9. Intake manifold or charge air cooler failure.
10. Intake manifold pressure sensor.
11. Turbocharger failure.
12. Fuel doser injector valve leaks.
13. Failed cylinder injectors.
14. DPF failure.
15. Perform a stationary regen.

WARNING!