Is that true?

 

Maybe, but it could be the MAFS, high fuel pressure, leaking injectors, slight misfires, and some others that I haven't heard about.

 

If your running rich its either what RJ posted or you've got an air leak (vacuum or otherwise) which is causing the ECU to richen up the mix. That in turn can mess up your O2's...are you getting a code?

 

Usually a dirty MAF sensor. Clean only with MAF sensor cleaner, be careful not to bend any pins, and then tighten all of the hoses between the Throttle body and air cleaner; check the air tube for tears.

And you car is a ?