Some 2003-05 V6-equipped Nissans (complete vehicle list below) may come into your store with an illuminated Check Engine light and/or hard restart issues when the engine is at operating temperature. If you connect your scan tool, you'll probably pull cam sensor trouble code P0340 and/or P0345 from computer memory. Installing new-design cam sensors should help eliminate all the problems immediately. Order part # 23731-6J906 for the P0340 code; part # 23731-AL616 for the P0345 code. Nissan recommends replacing both sensors if the two codes are stored or if you have no codes but do have the hard restart issue.
Models that can benefit from the updated cam sensors are 2003-04 Altimas, 2004 Maximas, 2004 Quest minivans built before 3/1/04 and 2005 Altimas built before 2/26/04.