confused on "limp" mode

[Slow_LS]

i have a CEL for my o2 sensor so does tha mean my car is in "limp"mode, and what exactly does that mean/do to my car? does that mean it isnt as fast as it should be? i know that it kills my gas, i get shitty gas mileage now. but i have a new o2 and new bung and what not but dont have anybody to weld the new one on so i can move the hole a little farther down.

 

[Samurai_Blue]

limp mode is "get home safe" mode, your gas milage sucks because you are running rich due to the o2 you are not in limp mode