Intake air leak
Faulty O2 Sensor
Faulty Mass Air Flow (MAF) Sensor
O2 Sensor harness is open or shorted
O2 Sensor circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
Long Term Fuel Trim Add. Fuel B2 System Too Lean is the generic description for the P1138 Audi code, but the manufacturer may have a different description for your model and year vehicle. Currently, we have no further information
about the P1138 Audi OBDII code.