just got some codes read....a little help!
 

I just got back from autozone where I got my codes read because my check engine light came on several days ago...I got:

P0400, the PCM has determined that a malfunction exists in the EGR flow,

P0150, PCM has determined that a malfunction exists in the electrical circuit for O2 sensor 1 in bank 2

P0130, PCM has determined a malfunction exists in the electrical circuit for O2 sensor 1 in bank 1....

WHat could be causing these problems? Do I just need to replace O2 sensors or could the problem be deeper? What about the EGR valve? Should I replace as well?

does anyone know how to locate the correct O2 sensor? I flushed the EGR system but I still have a CEL! Last time I went to autozone, only the egr and 1 O2 sensor code came up....can any one tell me why one of the O2 codes would dissapear? I want to replace this O2 sensor but I dont know which is which.....is there any easy way to find out which one I need to replace (after I hit up autozone again and get a code reading to find out specifically which one is bad?) Also, it says a malfunction exists in the elcetrical circuit....is this just a bad O2 sensor or something else?

P0150- 0303
Diagnostic Trouble Code 0303 indicates a problem with the front Oxygen Sensor on the left cylinder bank. The left bank is also called the front bank. It is cylinders 2,4,6. A normal signal sweeps back and forth between 0.2 volts and 0.8 volts. This malfunction was detected when the Engine Control Module received a signal from the sensor which was a constant value of approximately 0.3 volts.

Possible causes include ...
- Harness or connectors (the sensor circuit is open or shorted).
- Defective Oxygen Sensor



P0130 - 0503
Diagnostic Trouble Code 0503 indicates a problem with the front Oxygen Sensor on the right cylinder bank. The right bank is also called the rear bank. It is cylinders 1,3,5. A normal signal sweeps back and forth between 0.2 volts and 0.8 volts. This malfunction was detected when the Engine Control Module received a signal from the sensor which was a constant value of approximately 0.3 volts.

Possible causes include ...
- Harness or connectors (the sensor circuit is open or shorted).
- Defective Oxygen Sensor