Hitachi Fault Code
Free · no signup10042-12 (SPN 5246 FMI 12)
Red "Stop Engine" lamp; Immediate or timed engine derate; 5 MPH/Low Idle lock.
System
Not specified
Symptom
Red "Stop Engine" lamp; Immediate or timed engine derate; 5 MPH/Low Idle lock.
Diagnosis & fix steps
SCR Operator Inducement - Internal Component Failure.
LOGIC: This is a "Critical Inducement." The machine's DCU (Dosing Control Unit) or the Engine ECM has detected a severe internal error or a long-standing emissions violation that has timed out.
ACTION: 1. Use MPDr. (Hitachi Service Tool) to check for "Root" codes like NOx sensor or DEF Pump failures.
2. Check the DCU main power relay.
3. Inspect the communication (CAN) link between the engine and the SCR controller.
FIX: Address the underlying SCR hardware failure (Pump, Doser, or Sensor); perform an "Inducement Reset" using the service tool to unlock the machine.
Red Seal field insights
On Hitachi machines, this code often "latches." Even if you fix the broken wire or bad sensor, the 10042-12 code will stay active until a technician performs a manual "Emissions Trip Reset" in the software. You cannot clear this by simply disconnecting the battery.
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