My mom has a 2002 Discovery that won't pass emissions, but it runs normally otherwise.It was taken to the dealer, and they found a P0171 & P0174 code. They replaced the MAF sensor. They said they weren't able to drive it long enough for the ECM to recognize the drive cycle? I'm not sure what that means? I'm pretty handy with a wrench, but I'm unfamiliar with Land Rovers. Where should I start. Any help would be appreciated.