Errir code P2100

Hi

Local garage did some work on the front of the car and removed the bumper and o/s wheel arch. New Battery and horns.
since then mpg has been around 10-15 mpg as indicated on a scanguage i have fitted into the odb socket. I checked for eror codes and got 2
P2100 and then what looks like every time i do a check for the second code it changes POD24/POCE8/POOCC etc

But no warning lights.

Any ideas?
 
They cleared code but said thottle body may be faulty or need cleaning. I cant find a how to clean throttle body on the forum. Can anyone help please?