LongfinsGT

can anyone tell me about this code 5284. i cleared it on my car and it doesnt come back for a couple days then it just pops up. second time i have got it in 3 months. Does it efect the car? Where is the sending unit so i can replace it? or a way to test an see if it works? i just put my pulleys on and started getting it after we did them. I sealed the key whole its not leaking. would that be a part of the code? thanks for the help everyone