Code says APP Sensor should be replaced so how to check this before I replace

 

Even the basic OBD scan tools have the ability to read the input on accel pedal or throttle position. With the key on, engine off, I would look at the sensor data to make sure it sweeps from 0-100% by depressing the pedal to make sure the sensor output covers all percentages. If not, there would be an issue in the pedal assembly or the TPS on the intake manifold. Normally TPS issues would be accompanied with hesitation at certain throttle inputs as the circuit becomes open, and signals 0% throttle input, so I'm not sure if you have those symptoms also?

 

speaking of past personal experiences with other honda products... before you start replacing APP Sensors, look at the carpet and in that area if there is anything that prevents the gas pedal from going all the way to the floor. Just a thought...

 

or something that keeps it all the way to the floor like unrestrained floor mats from an early model Prius

 

Well before we can help you we need to know what year, sub-model and transmission this regards.
There can be vast differences between some of the model years in the 4G category.

There are several versions (different years) of the service manual in this forum. Search to find them.
The service manual describes how to test all the sensors and more specifically, how to troubleshoot specific error codes.

Good luck and let know what you do to correct the issue.