Bank 1 Vs Bank 2 | Where is Bank 1 Sensor 1 located?

The vehicle has multiple sensors. These sensors are the most important parts of the car. An oxygen or O2 sensor is installed in the vehicle’s engine, which needs to be replaced after a short time. Oxygen cylinders or O2 cylinders have divided into two categories, bank 1 and bank 2. Bank 1 and bank 2 represent the engine sides. Bank 1 represents the side of the engine in which the 1st cylinder is installed.

What are Bank 1 and Bank 2?

Bank 1 and bank 2 represent the two sides of the engine. Although the location of bank 1 and bank 2 is tricky to find. The location of bank 1 and bank 2 varies from vehicle to vehicle according to their model number.

To find out about bank 1, you must see where the number 1 cylinder is located. Bank 1 denotes the engine side where cylinder 1 is installed, while bank 2 denotes the engine side where cylinder 2 is installed.

In the case of a transverse engine, bank 1 is located towards the front of the car.

  1. Bank 1 is located on the engine side with cylinder 1, i.e., cylinders 1,3,5, 7 (odds)
  2. Bank 2 is located on the engine side with cylinder 2, i.e., cylinders 2,4,6,8 (evens)

Bank 1 vs Bank 2

The easiest way to detect the right bank number is to review the car’s repair manual. In car manuals, the oxygen cylinders are labeled with the exact numbers and the banks.

Another easy way to find out the cylinder number is to see for any stamp on oxygen cylinder heads or at their blocks in your car’s engine.

The crankshaft pulley is placed at the front of the engine, but still, we can’t exactly find if bank 1 is at the driver’s side or passenger’s side. As we discussed that different cars could have different locations of cylinder 1. So, it is always confusing to confidently point out the exact location of bank 1 and bank 2.

The picture above illustrates the types of engines based on the location of the number 1 cylinder. The cylinder near the front of the car’s engine is usually cylinder number 1; hence the side with cylinder 1 will be bank 1, and the other side will be bank2.

Locations of Oxygen Sensor

The location of the O2 sensor varies according to the location of the oxygen cylinder and bank number.

Location of Bank 1, Sensor 1

Technically, the oxygen sensor (sensor1, bank1) of the vehicle is located upstream or ahead of the catalytic converter on the bank, which links to the first cylinder of the engine. That is because bank 1 is the side with the engine’s first cylinder, and sensor 1 works as an upstream spot.

Location of Bank 1, Sensor 2

Likewise, the O2 sensor (sensor 2, bank 2) of the car is installed downstream or behind the catalytic converter on the bank, which links to the 1st cylinder of the engine. That is because bank 1 is the side with the engine’s first cylinder, and sensor 2 works as a downstream spot.

Location of Bank 2, Sensor 1

Bank 2 is on the opposite side of bank 1. The O2 sensor of the vehicle (sensor 1, bank 2) is installed upstream or ahead of the catalytic converter on the bank, which links to the 1st cylinder of the engine. That is because bank 2 is the side with the engine’s second cylinder while sensor 1 acts as an upstream spot.

Location of Bank 2, Sensor 2

Correspondingly, Bank 2, sensor 2 is located downstream or behind the catalytic converter. That is because Bank 2 is the side with the engine’s second cylinder, and sensor 2 acts as a downstream spot.

Upstream and Downstream Sensors

Now, you must be wondering what upstream and downstream sensors are?

Upstream sensors are the ones that are installed above the catalytic converter, while downstream sensors are installed behind the catalytic converter.

O2 sensor location

A conventional method to locate the oxygen cylinders in any vehicle is to relate the location of the O2 sensors to their upstream or downstream orientation. By going through the diagram below, you can better understand where exactly upstream and downstream sensors are in your vehicle.

The exhaust of any vehicle has two independent O2 sensors for bank 1 and bank 2, one of them is upstream, and another is downstream.

Here, the terms upstream and downstream represent the positioning of the oxygen sensors according to the exhaust catalyst according to the flow direction of the vehicle’s exhaust gases. An easy way to understand this flow phenomenon is to imagine the “exhaust flow” as the “flowing river or stream.”

How to locate O2 Sensor through an OBD2 Scan Tool

OBD2 is a scanning tool used to locate a sensor’s exact location. This locating process took only a few minutes to complete the whole locating process in a very short period.

OBD2 scan tool

Using the OBD2 scan tool helps to locate the oxygen sensor more efficiently in minimum time and thus eliminates the chances of replacing the wrong oxygen sensor from the engine bank. In short, it saves both money and time.

To find the exact oxygen sensor, you must turn “ON” your vehicle’s ignition.

After that, insert the OBD2 tool on the next subsequent port. As a next step, you must disconnect every oxygen sensor one by one and note the active code logged readings on the scan tool.

With the disconnection of any oxygen sensor, this scanning tool shows the “voltage high” or “open” code at the subsequent position of the specific sensor reading on the scanning tool.

Now, connect that Oxygen sensor again, and after initiating the vehicle’s ignition, this DTC should now be eliminated. You must continue that process of disconnecting and connecting each sensor until you find the exact sensor you were searching for.

FAQ Section

What is an O2 sensor?

As O2 is the chemical formula of oxygen, the O2 sensor is the term used for Oxygen sensor. This O2 sensor is used to gauge how much oxygen is left unburned in the exhaust of any vehicle. Monitoring these oxygen levels indirectly helps in measuring the fuel mixture.

How can we clean the oxygen sensor?

There is not any specific cleaner that you can use in your car’s engine. Some people use aerosol cleaner or wire brush to clean their vehicle’s oxygen sensor, but it can damage the oxygen sensor and results in its failure. Hence, we do not recommend cleaning the oxygen sensors.

Do bank 1 and bank 2 both have the same sensors?

Usually, the sensors used in both bank 1 and bank 2 are the same. Still, it can be varied with car model and sensor type. You must check your car repair manual, or you can ask your car dealer to find out if your car model has the same sensors or not.

Can we find if bank 1 is on the exhaust or intake side?

No, we can’t find the position of bank 1 from the exhaust or intake side. Bank 1 is the side with cylinder 1, and bank 2 is with cylinder 2.

Is bank 2 at the front or rear of an engine?

The position of a bank cannot be detected by reviewing the front or rear side of the engine. Bank 2 is the side where cylinder 2 is installed.

Can we detect if bank 1 is on the driver’s side or the passenger’s side?

Yes, bank 1 can be on the driver’s side in most cases, but it can’t be followed blindly. bank 1 is the side of the engine with cylinder 1. If you go with the guess, there will be just a waste of money and time.

Is it okay to drive with a faulty oxygen sensor?

Yes, you can drive when your car’s oxygen sensor is faulty or in bad condition. Faulty oxygen sensors result in consuming more fuel than the regular fuel intake of your vehicle. Hence it is good to replace the faulty oxygen sensor soon to avoid more fuel consumption and spending more money in the future.

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