Trouble code P1274 in a Nissan Maxima is defined as Air/fuel sensor reading a rich fuel mixture. It also points to the upstream AF sensor on Bank 1 (the side of the engine near the firewall). The AF sensor is also referred to as the oxygen sensor located on the exhaust manifold before the catalytic converter. Depending on how many miles the car has, this sensor might need replacing. Technicians do recommend replacing both upstream sensors as the AF sensor on Bank 2 (the side of the engine near the radiator) might go bad as well. Other causes of trouble code P1274 are faulty injectors, improper fuel pressure, or a malfunctioning Mass Airflow Sensor.
If you wish to clear the codes temporarily, simply disconnect the negative battery cable. Wait a couple of minutes, then reconnect. If no repair was performed, the trouble code light might return after a few miles of driving. State Inspection requires that all monitors are ready during emissions testing, so make sure that you have completed a drive cycle (about 3 days or 50 miles of driving) before submitting the vehicle for an emissions test.