2002 Nissan Altima Do I?

The fender well has a purpose, like everything on the vehicle. But like many parts only serves that purpose in the long run or at certain times.

Fender wells prevent water, dust, mud sometimes road-kill from entering your engine compartment. Water and dust make mud which can corrode wire in the long run. A tire "blow out" could throw something into you accessory drive belt area and do some damage.

The car will run fine without it for a long time if you don't want to look for one. On the other hand try calling a few wreckers to locate one, it is easy to install.

Good luck.