My sister has a 2007 Versa with 34k miles. The service engine soon light came on. The PCM is throwing code 2A00, B1 A/F .. I assume that is the Ox sensor. I wish I had gotten her a Chevy Cobalt instead. She lost a key now only has one . The dealer wants 100's of $$ for a second key. When we bought the car the dealership tried that Dealer profit trick.