My neighbor has a 2008 Land Rover Range Rover Sport and got this code. It seems that it would indicate that hits his catalytic converter has gone bad. I suggested that he use spark plug non-foulers after researching the matter online. He installed the non-foulers and installed on the uppermost O2 Sensor on the passenger side. I have a couple questions, which location should the non-foulers be installed? The next question involves the CEL as it initially went out but came back on suggesting the fuel injectors need to be cleaned. Any suggestions?