Detroit DD13 EPA07 (2007-09) Fault Code: SPN 3242 FMI 8 (MCM) Motor Control Module Has Detected an Impossible Temperature Shift on the Diesel Oxidation Catalyst Inlet Temperature Sensor

Posted by PerDiezel Solutions on March 8, 2026

NOTE: If 3242-3, 3242-4, 3242-8, 3250-3, 3250-4, or 3250-8 present, fix those first.

PROBABLE CAUSES:
1. Compare DOC inlet, DOC outlet, and DPF outlet. They should be within 45 degrees of each other.
2. DOC inlet temperature sensor.
3. DOC inlet temperature sensor connector/harness.
4. DOC outlet temperature sensor.
5. DOC outlet temperature sensor connector/harness.

WARNING!