I found out that my AIR pump had gone bad so i had it replaced, both the mechanic and i thought that would fix the problem. So today i get the car back and i drive for a while to reset the computer. Before i would usually get the code 12 miles or so after i reset it. 12 miles came and went and i was pretty happy. Then i got to about 23 miles and the check engine light came on agian. So i checked the codes and it was P0410 and P0420 for secondary injection system and low cat efficiancy. I knew the pump was bad, when we took it out it wouldn't turn at all. Could it be a bad 02 sensor? I also get a knock at 4 or 5 thousand rpm. Could an 02 sensor cause that?

 

It's possible that both O2's are bad but not likely. If only one of the O2's was bad, it would set a 1415 or 1416 to let you know what bank the problem was on.

chances are either the pump is not comming on like it should or there is something wrong with the vacuum source. check the AP fan fuse and all the vacuum hoses to and from the solenoid.

However, since the 420 refers to bank one, swap the after cat O2s from side to side and reset all codes and let it warm up to closed loop. Then go from there based on what codes now appear.