The term "bank" refers to a group of cylinders within an engine. Most engines have two banks, numbered 1 and 2. Here's how it breaks down:

- Bank 1: Typically contains cylinders 1, 3, 5, and 7 (for a V8 engine).

- Bank 2: Houses cylinders 2, 4, 6, and 8 (for a V8 engine).

Sensor Numbers

O2 sensors are also numbered as Sensor 1 and Sensor 2 within each bank.

- Sensor 1: Located upstream (before) the catalytic converter. It provides real-time information to the ECU for immediate adjustments to the air-fuel mixture.

- Sensor 2: Situated downstream (after) the catalytic converter. It monitors the efficiency of the catalytic converter in reducing emissions.