Bank 1 refers to one side of the cylinder, and either Bank 2 refers to the other, whether or not the engine is an inline or a transverse engine.
It is simply stating either the right side or left side of an engine, but like everything else, it is not that simple. This naming convention is solely dependent on the manufacturer and the type of engine.
Bank 1 and bank 2 locations on an engine can be tricky. However, with the right knowledge about the engine type, it is straightforward about which is which. If you can identify which cylinder is number 1, it is also clear which is bank 1 or bank 2.
The easiest way to identify bank 1 is, to look at the vehicle manufacturer’s manual.
There are other ways to know either bank, such as looking up the crank casing, looking up the cylinder block, etc., but the easiest way is in the vehicle’s manufacturer’s manual.
What are Bank 1 and Bank 2?
Bank 1 and Bank 2 are the two sides of the engine. Bank 1 means the side of the engine with cylinder #1 and Bank 2 means the side of the engine that has cylinder #2.
The location of bank 1 and bank 2 is not easy to determine. Bank 1 and Bank 2 will differ from vehicle to vehicle for that vehicle model number.
To find out about bank 1, you need to find out where the number 1 cylinder is located. Bank 1 is the side of the engine with cylinder 1, and Bank 2 is the side of the engine with cylinder 2.
In the case of a transverse engine, bank 1 will be at the front of the car.
- Bank 1 is located on the engine with cylinder 1 or cylinders 1,3,5, 7 (odds).
- Bank 2 is on the engine that has cylinder 2 or cylinders 2,4,6,8 (evens).
The easiest way to determine the correct bank number is to reference the car’s repair manual. In repair manuals, oxygen cylinders are labelled with the exact numbers and numbered Bank.
Another easy way to find out the cylinder number is to look for any stamp on oxygen cylinder heads or at the blocks on your cars engine.
The crankshaft pulley gets mounted on the front side of the engine, but that still doesn’t tell us if bank 1 is on the driver’s side or the passenger’s side.
As we discussed earlier, different cars could have the number 1 cylinder mounted in different locations or different sides of the car. So, it is always confusing to say exactly with confidence if bank 1 is on the driver’s side or passenger side.
How to locate an Oxygen Sensor
Location of the O2 sensor varies depending on the position of the engine cylinder and bank number. The position of the different oxygen sensors is located below depending on the bank number:
Bank 1 Sensor 1 Location
The oxygen sensor (sensor1, bank1) is in the vehicle, located upstream or ahead of the catalytic converter on the bank linked to the engine’s first cylinder. That is because bank 1 is the side with the engine’s first cylinder, and sensor 1 is upstream.
Bank 1, Sensor 2 Location:
Similarly, the O2 sensor (sensor 2, bank 2) in the vehicle is also installed downstream or behind the catalytic converter on the bank linked to the 1st cylinder of the engine. Again, that is because bank 1 is the engine’s first cylinder, and sensor 2 is downstream.
Bank 2, Sensor 1 Location:
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 linked to cylinder 1 of the engine. Again, bank 2 is the side with the engine’s cylinder 2, and the sensor is upstream.
Bank 2, Sensor 2 Location:
Similarly, Bank 2, Sensor 2, is downstream or behind the catalytic converter. That is because bank 2 is the end with the engine’s second cylinder, and Sensor 2 is downstream.
Upstream vs Downstream
You may be wondering what upstream and downstream sensors are now.
Upstream sensors are the oxygen sensors that are located ahead of the catalytic converter; downstream sensors are located behind the catalytic converter.
A straightforward approach for determining the locations of the oxygen cylinders in any vehicle is to refer to the location of the O2 sensors in relation to whether it is defined as upstream or downstream of the exhaust catalyst. The diagram below will assist you in identifying where the upstream and downstream sensors are located.
Each vehicle’s exhaust has two independent O2 sensors for bank 1 and bank 2; one is upstream and one is downstream.
In this case, the terms upstream and downstream refer to the location of the oxygen sensors in relation to the exhaust catalyst in the direction of the exhaust gas flowing through the vehicle exhaust. A simple introduction to the flow process of exhaust gas is to refer to the “exhaust flow” as the “flowing river, stream.”
How to Locate an O2 Sensor Via OBD2 Scan Tool?
OBD2 is a tool used to pinpoint a sensor’s exact location. This can be done in just a few minutes to complete the whole locating process quickly.
Using the OBD2 scan tool is just a better way to locate the oxygen sensor as efficiently as possible and at a minimum time frame to prevent replacing the wrong oxygen sensor from the engine bank. It saves time and money.
The only thing you will need to do to find the exact oxygen sensor is to turn the ignition “ON”.
- Insert the OBD-II tool on the following port.
- Disconnect each oxygen sensor, one by one, and watch the active code logged reading on the scan tool.
- After disconnecting an Oxygen sensor, the scanning tool will show “voltage high” or “open” at that specific oxygen sensor position on the scanning tool.
- Reconnect that Oxygen sensor, and after turning the ignition on, that DTC should now be gone.
- Continue that process of disconnecting and reconnecting each oxygen sensor until you find the correct oxygen sensor you are looking for.
FAQs.
Q: What is bank 1?
Bank 1 is simply the cylinder 1 role. Therefore, regardless of engine type, position and location, the must and attachment of bank 1 to cylinder 1 is a must. . Usually, the bank will contain oxygen sensor 1 and 2. Thus, the identification of bank 1 leads to the automatic identification of bank 2 (the opposite bank).
It is important to note that either the driver’s side or passenger side corresponds to the location of bank 1. Although the vehicle and manufacture difference, the position of bank 1 will differ from vehicle to vehicle.
Q: Is bank 1 left or right?
Bank 1 is not considered a left or right bank for the engine and does not have a defined position; wherever it is, it just is.
As mentioned, it depends on the type of engine and the maker; however, bank 1 is more likely on the left than on the right, not definitive but likely.
Therefore, a bank 1 can either be left or right. Bank 1 is right on some engines and left on others. Thus bank 1 also does not have a definitive position on the engine.
Q: Is bank 2 driver or passenger side?
Bank 2 is not specifically the driver’s or passenger’s side. Just like bank one does not have a definite position or side, neither does bank 2.
Some are on the passenger side, while in some they’re on the driver’s side. This will all depend on the engine type and the manufacturer.
Bank two could be on either the passenger side or the driver’s side. It’s important to note that bank 2 is the direct opposite of bank 1 on every engine.
Q: Are bank 1 and bank 2 sensors the same?
Bank 1 and bank 2 have the same sensors. However, Bank 1 has two sensors. Sensor 1 is located near the engine before the catalytic converter, it is a pre-CAT (upstream sensor). Sensor 2 is located after the CAT (downstream sensor).
Bank 2 has its own Sensor 1 near the engine, before the CAT (upstream sensor) and sensor 2 (downstream sensor) after the CAT, so both bank 1 and bank 2 change are identical in every engine.
Q: Which 02 sensor is bank 1 sensor 2?
The oxygen sensor bank 1 sensor 2 is a post CAT sensor. The main function of this component is checking the activities of the catalytic converter and reporting it back to the computer engine.
Bank 1 sensor 2 is effectively checking the operation of catalytic convertor to determine tire performance of catalytic convertor.
The information is also for checking catalytic convertor performance minus any obstructions for checking operatinal performance. Bank 1 sensor 2 is post catalytic convertor.
Q: Is bank 1 upstream or downstream?
Bank 1, as stated above is, on either side of the engine, so bank 1 is not upstream or downstream as a category. Bank 1 is simply housing both sensor 1 and sensor 2, designated by the position of upstream and downstream sensors.
A bank 1 would have both upstream and downstream sensors. Bank 1 is associated with cylinder 1 and is not a determinate of upstream or downstream as it simply provides housing for different locations of sensor placements, which would indicate up and downstream as indicated earlier.
Q: Can you swap upstream and downstream 02 sensors?
Upstream and downstream 02 and Oxygen sensor swapping is not possible is because they have different functions and locations. For example, upstream 02 sensors are located pr-Catalytic convertor upstream and downstream 02 sensors are called post cat.
In distinctly simpler terms, swapping upstream and downstream is not possible for these reasons.
Any sensor swapping could result in the false reading of the 02 sensors, sending a error or inaccurate sensory signal to inform the vehicle’s computer causing the vehicle a malfunction.
Q: Is there a difference between upstream and downstream oxygen sensors?
There are many differences between the upstream and downstream 02 sensors as they have different locations and functions as mentioned previous.
The upstream 02 sensor is meant to be inputting into the data of the amount of air-fuel mixture that enters the engine and sends that data to the computer of the vehicle, hence upstream.
The downstream 02 sensor is intended to simply check if the catalytic convertor is working properly or if the catalytic convertor is deteriorating , with information sent back to the vehicles computer, and in added to know what are optimal conditions for performance. It would also check if there is a clog as well.
Final Words
It is important to understand that four-cylinder engines have only one bank. So, bank 1 vs bank 2 is not related to sensor 1 and sensor 2 in the bank. Bank 1 sensor 1 is also not to be confused with bank 2 sensor 1.
Once a clear understanding of what bank is established, either bank 1 or bank 2 for six-cylinder engines and above has sensor one and sensor two.
Sensor one is always permanent in location for a sensor one, because they are always located before the Catalytic converter. Sensor two is also permanent in location for a sensor, because they are permanently located after the catalytic converter.