What is Bank 1 and Bank 2?
The term "Bank" in automotive is used by the manufacturer to identify the side of the engine. For example, on some vehicles "Bank 1" is assigned to the left side of the engine, if there were a problem with the oxygen sensor on the left side of the engine, the manufacturer's definition for the engine’s left side Oxygen Sensor would be "Oxygen Sensor Bank 1". Manufacturers identified the engine sides differently. Some manufacturers may assign the left side of the engine as Bank 1 and the right as Bank 2. The best way to determine which side is Bank 1 or Bank 2 is to check the vehicle's service manual. On most vehicles, Bank 1 refers to the side of the engine where the #1 cylinder is located.