what would cause an error code p138 and how can i fix it.also had another code that was p0054

This is a lean condition on bank one, sensor 2. Either your 02 sensor has gone bad (likely), or your car is in need of a tune up.

A lean condition menas not enough fuel,or too much air. Dirty injector?Vacuum leak? Check the long black crankcase hose that runs across the top of the motor. I had an Aveo,and had to replace this.We replaced it with braided line.It was much cheaper than the replacement part. Also check the rubber "hose" that mounts on the airflow meter.Mine was leaking air into the system.