The r has 4 sensor, 2 rows each ahving two on it. Each row is called a bank, so bank 1 and 2. I think bank 1 is the drivers side, but i cant totally remember. But if its a problem it should also say sensor 1 or sensor 2, with sensor 1 being pre cat and sensor 2 being post cat.
if your stuck plug it into the computer and disconect one of the sensors undo the black box and pull the conection apart. then check which is bank 1 and 2, then use that info to replace the one that is dead
Im getting that stupid fault code 16804 - Catalyst System: Bank 1: Efficiency Below Threshold. At first I thought it was the cat, but my friend who's also a mechanic had the same code and it turned out to be the o2 sensor.
You can drive for miles around town but as soon as you get on the motorway for long journies the emission light comes on.
i had this same code and it was the cat that was gone. but im not sure what side is what. you could always swap post cat sensors around and if problem goes to bank 2 i will be the cat if it stays the same it will be the sensor. as the cats are completely seperate usually only one side goes. hope that makes sense