Diagnostic code reads : Too rich on bank 2?

Could be O2, A simple way to find out if the plugs are the problem is to pull the plugs on Bank 2 (That should be the back/ right side) and check them with the Recommeded plugs. I think what they are getting at is the plugs installed could be a colder plug then what is needed. This would cause a rich state on that bank. If thats the case the plugs are the cause. If not then check the O2 Senor. if after checking that your still having problems it's likely you have an injector that is leaking and causing a rich state. to repair this you would need to replace the injector.

The O2 sensor adjusts the fuel ratio through the cars computer, it is hardly likely that one bank would be affected unless you have dual exhausts with an O2 sensor on each side. Codes do not pinpoint the problem, but do give the technician an area to check. Assuming your shop has a good scanner and scope they should be able to isolate ( plug into the OBII outlet) the problem either in the shop or test driving to check the short and long term fuel trim, as well as fuel pressure etc.

It could be an O2 problem, but It also could be that you have an injector that leaks fuel into the engine that is Unmetered. Cylinders 1, 3 and 5 are bank 1 and they are on the passenger side. Cylinders 2, 4 and 6 are Bank 2 and they are on the drivers side. Have the shop check to see if the injectors are bleeding down after shutting the engine off. It's a very simple test with a fuel pressure gauge.

Were you given a numeric code? That would be key to be able to answer your quaestion better. I don't hink the plugs woudl affect bank 2. Could be a bad o2 sensor or a loose gas cap.