2013 sport (bought used a few months ago, so I don't know the history)

Very suddenly my car had the Vehicle Stability Assist & Check Engine lights come on. The car went into limp mode. The auto parts store scanned it and told me the error code is p2101.
When I called a mechanic, he told me that it might be 3 things. The throttle body, the pedal sensor, or the relay. He said finding out which one would be an hour of shop time. Does this sound legit? Is there an easy way for me to check myself?

Also, I'm mechanically inclined, and have worked on many different things in many different cars (mostly because I'm usually poor), but have never worked on any of those parts I listed. Looking at pictures of these parts makes me think that they prob aren't too hard for me to replace, but would welcome feedback on that thought though.

Lastly, how much risk is there if I buy a used one? A new throttle body is freaking expensive.

Thanks & any suggestions welcome.

 

Some guys on Honda-tech had luck cleaning out their throttle body and checking the connector.

 

Update for anyone who searches here later.
My neighbor found instructions online for getting the throttle sensor & the pedal sensor to sync back with each other and it seems to have worked.
Sorry, I don't have the website of instructions.