Oxygen Sensor/Check Engine Light

Here's more about oxygen sensors and what/where certain banks/sensors located.

On a scan tool, the downstream sensor on a four or straight six cylinder engine with single exhaust is typically labeled Bank 1, Sensor 2. On a V6, V8 or V10 engine, the downstream O2 sensor might be labeled Bank 1 or Bank 2, Sensor 2. If a V6, V8 or V10 engine has dual exhausts with dual converters, the downstream O2 sensors would be labeled Bank 1, Sensor 2 and Bank 2, Sensor 2. Or, the downstream oxygen sensor might be labeled Bank 1 Sensor 3 if the engine has two upstream oxygen sensors in the exhaust manifold (some do to more accurately monitor emissions).

Get a 5gas analysis it will tell whether the Cat is doing its job and where the cause is.

Verify that your o2 sensors are working. Give it a large vacuum leak and see if your o2 sensor 1 and 2 should drop down to 100 mv by adding fuel it should rise to 900 mv. Once you verify that the 2 o2 sensors are working you can use them to check the cat. @ 3000 rpm or driving @ a hi speed the front o2 should be switching from rich to lean. 200 mv to 900 mv. If the rear o2 is switching as quick as the front o2 your cat has failed and can't store oxygen