Cummins ISB CM850 (2003-06) Fault Code: 1242 PID: SPN: 91 FMI: 2 Accelerator Pedal or Lever Position Sensor Number 1 and Number 2 – Data Erratic, Intermittent, or Incorrect. Accelerator position sensors numbers 1 and 2 are reading different values.

Newer engines use two throttle position sensors to determine the throttle position. Older throttle pedals used a single throttle position sensor and an idle validation switch. If Fault Codes 132 and 1241 are active when the accelerator pedal is in the idle position and Fault Code 132 goes inactive and Fault Code 1239 goes active when the throttle is depressed, the incorrect throttle pedal has been installed in the vehicle. A throttle pedal with two acceleration position sensors should be installed.

This fault code becomes active when the accelerator position sensor number 1 and accelerator position sensor number 2 are not reading the same value.

Possible causes:

1)Failed accelerator pedal position sensor 1 or failed accelerator pedal position sensor number 2.
2)Accelerator pedal position sensor number 1 and accelerator pedal position sensor number 2 signal wires are shorted.

Possible repairs:

1)Repair or replace the OEM harness.
2)Replace the accelerator pedal.