Cummins ISX CM870 (2003-06) Fault Code: 443 PID: S221 SPN: 1043 FMI: 4/4 Accelerator Pedal Position Sensor Supply Voltage Circuit – shorted low. Low voltage detected at sensor supply circuit to the accelerator pedal position sensor.

Low voltage on the +5 volt supply line can be caused by a short circuit to ground in the supply line, a short circuit between the supply line and return circuit, a failed accelerator, or a failed ECM power supply.

Possible repairs:

1)Replace the accelerator pedal/lever position sensor.
2)Repair or replace the OEM harness.