P0300 is random misfiring and can be due to P0173, which might or might not be du eto it being faulty. There are other possible causes for them to be triggerred.
DTC P1173: LEFT FRONT OXYGEN SENSOR, INVERSION
DTC is set when left front oxygen sensor signal voltage exceeds.45 volt and remains unchanged for 42 seconds after engine is started and has reached normal operating temperature. Engine speed at 1150 RPM or greater. Possible causes are:
Left front oxygen sensor.
Open or short circuit between terminal No. 3M on Powertrain Control Module (PCM) and terminal "A" (Yellow wire) on left front oxygen sensor.
It is recommended that the following components and/or systems be inspected to ensure proper operation. Deterioration or malfunction of following components and/or systems could contribute to DTC P1173 being set:
Fuel Pressure Regulator
Air Intake System
Purge Solenoid & Hoses
Mass Airflow Sensor
Thursday, January 3rd, 2013 AT 1:42 PM