cat update hpk articles do not indicate any updated accerator pot that includes installing an external switch that i can find.

But code 51 does involve replacing the potentiometer or repairing any wiringi issues or abnormalities in the accelerator circuit or pedal assembly.

make sure the pedal is returning completely back when released.
if any wiring is found to be chafed or broken repair the wiring
if all else fails then replace the accelerator potentiometer and set it up according to cat adjustment proceedures.

Note: installing an external switch negates any safety protocols and should not be done in ANY case.