I've never seen the wif light come on either. have a good buddy with an 06, he apparently got into some really bad fuel a while back. the dealership ended up replacing all 8 injectors, im not sure that was all necessary but anyway...they said there was a ton of water in the fuel. his wif light never came on. however if it was my truck i would repair the thing because you never know when it may save you some big trouble.