OBDII - Articles - What is Bank 1 and Bank 2?

What is Bank 1 and Bank 2?

- Last Edited: Aug 27, 2023
- Popularity: 5,148 Views


The terms "bank 1" and "bank 2" are used to refer to the two sides of an engine. In a V-shaped engine, the banks are the two "Vs" that make up the engine. In an inline engine, the banks are the two rows of cylinders.

Bank 1 is always the side of the engine that contains cylinder number 1. Cylinder number 1 is always the cylinder that is closest to the front of the engine. Bank 2 is the opposite side of the engine from bank 1.

The terms "bank 1" and "bank 2" are often used in conjunction with other terms, such as "oxygen sensor" or "catalytic converter." For example, an oxygen sensor that is located on the bank 1 side of the engine would be referred to as "bank 1 sensor 1."

The terms "bank 1" and "bank 2" are also used in diagnostic codes. For example, the OBD-II code P0130 refers to a "Bank 1 Sensor 1" oxygen sensor malfunction.