Bank 1 Vs Bank 2 Sensor (1 & 2 Oxygen Sensors Location)

Oxygen sensors have the shortest lifespan in a vehicle, which makes them one of the most replaceable components. Because they are essential components of a car, you cannot risk replacing them at the right time if at all you value the performance of your vehicle.

In case any of your car oxygen sensors have stopped working, you must first inspect the vehicle; find out which one of the sensors is faulty then fix them professionally.

If you are a new motorist on the road, or you just owned your first car recently, there are many parts of the vehicle you may not be familiar with. Most people find it a bit challenging to locate bank 1 and bank 2 sensors.

It sounds a bit confusing to locate the different oxygen sensors in your vehicle. Once you get used to them, it is never that complicated to identify and replace them correctly.

Bank 1 Vs Bank 2 Sensor

Most people have replaced oxygen sensors in their cars the wrong way because they did not know which ones they ought to replace. Therefore, we have prepared this article to keep you updated. Keep reading to stay informed on how you can locate oxygen sensors and replace them on time.

Bank 1 Vs Bank 2 Oxygen Sensor

Locating bank 1 and bank 2 is the most confusing thing for any car owner, especially if you are driving your first car. Your car engine cylinders are divided into two different parts. For a V-engine, you can locate a bank at either side.

On the drivers’ side is bank 1, and on the passenger side, you can find bank 2. However, because people drive on different sides, it is not appropriate to use that technique to identify the banks.

So, here is a rule of thumb:

Bank 1 is located on the engine side with cylinder numbers 1, 3, 5, 7, and 9, while bank 2 is located on the engine side with cylinder 2, 4, 6, 8, etc. You can see the pattern, right?

It essential that you first identify the type of cylinder (whether it is type 1 or 2) before you can proceed to determine the type of bank.

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Locating Oxygen ( O2 ) Sensors in Your Vehicle

Oxygen sensors, also known as O2 sensors, come in two categories; the bank 1 sensors and bank 2 sensors. The sensors are again subdivided into two different categories and given different sensor numbers – it can be either sensor 1 or sensor 2.

Because of the different categories of oxygen sensors, most people find it confusing to locate the right sensors, and they end up replacing the wrong ones. It is difficult to locate which O2 sensor is bank 1 and which one is bank 2 if you don’t have some prior knowledge of how to locate them.

Replacing the wrong sensor will cost you time and money. So, it is crucial that when your vehicle oxygen sensors are not working properly, you simply locate the spoilt ones and replace them.

You can easily locate O2 sensors using the following methods:

  • By using the OBD2 scanner
  • Manual method

Let us explain how you can apply the above two methods to save yourself the hustle of identifying and replacing your oxygen sensors.

Method 1: The Manual Method of Locating Oxygen (O2) Sensors

Step 1: Find Bank 1 and Bank 2

We have explained what bank 1 and bank 2 means in the previous section of the article. If you want to locate the different banks and sensors in your car engine system, you must first understand the type of engine you have.

Generally, there are two types of engines, transverse engine, and inline engines. Most manufacturers mount transverse engines in the opposite direction. If you know how to identify the different types of sensors, the design or mounting of your car engine may not cause you any trouble.

As mentioned earlier, bank 2 will always be on the cylinders marked with even numbers like 2, 4,6,8,10,12, and so on. Alternatively, you can find bank 1 on cylinders marked with odd numbers like 1,3,5,7,9,11, etc.

Step 2: Locate the Cylinders 

Once you’ve identified bank 1 and bank 2 on your car engine, the next challenge is to locate the different cylinder numbers. Here is how you can go about it.

In some cases, the ignition cables used to connect the cylinders may have the cylinder numbers marked on them. However, if you repaired your engine before, it is not wise to use the cables in identifying the cylinders – your mechanic may have replaced them in different positions.

Check the crankcase cover if there is a cylinder number written or stamped there.

Look up your repair manual or service manual for the order of cylinders. This is the safest way of locating the cylinders. If you don’t have your user manual, you can ask your car dealer for help.

If you have your engine code or cylinder order, you can search for the information on the internet.

Step 3: Find the sensor numbers.

The last step is to find the sensor numbers, and that means you should be able to tell the different types of sensors in your car engine.

A sensor number tells you where the oxygen sensor or the exhaust temperature sensor is mounted on the exhaust system. Sensor 2 is normally located at the rear of the vehicle’s exhaust system, while sensor 1 is located the closest to the engine.

You can also say that senor 1 is found before the catalytic converter front, while sensor 2 is located after the catalytic converter front. That is why sensor 1 is also known as upstream O2 sensors, and sensor 2 is known as a downstream O2 sensor.

In some cases, a vehicle may have up to 4 sensors (for instance, cars with diesel engines) because they have a lot of exhaust temperature. If you have a diesel engine with four O2 sensors, you will find sensor 1 nearest to the car engine and the sensor 4 furthest to the car exhaust system.

Method 2: Using OBD Scanner to locate Oxygen (O2) Sensors

It is much easier and faster to locate oxygen scanners in your car engine with an OBD scanner at your disposal. Follow these steps to find out bank 1 and bank 2 in your car engine.

  • Connect the OBD scanner and erase all the trouble codes in the device.
  • Countercheck that no trouble code is left
  • Unplug one of the O2 sensors (it doesn’t matter which one you choose) then proceed to check the DTC code.

The DTC code will tell you which one is bank 1 and which one is bank 2. You can easily tell which one is your bank 1 or bank 2.

Using the OBD scanners is one of the safest ways to identify oxygen sensors in your engine and ensure you replace the right ones. Sometimes you may get a DTC code P0420, which is normally triggered by a fault in the oxygen sensors.

In this case, you have to troubleshoot the o2 sensor and fix the errors. A leak in the exhaust system is likely to be the cause of this error code. Ensure you fix it before you can proceed to locate the oxygen sensors.

Why you should Replace Oxygen Sensors on Time

Your car engine does not need you to replace oxygen sensors regularly. You only need to replace the sensors when they fail. Unlike oil and air filter, they may last a bit longer.

Oxygen sensors are an integral part of the car exhaust system. They keep checking the level of oxygen in the exhaust system and send that information to the vehicle’s engine computer. The engine adjusts the air-to-fuel ration appropriately to ensure a balance in fuel consumption.

If your vehicle has faulty or broken O2 sensors, the engine cannot adjust the air-to-oxygen ratio accordingly, and this will result to fuel wastage. Also, your car may experience an overheated catalytic converter, higher emissions, and severe damage to other essential parts of the engine system.

It is not easy to find out if your o2 sensor in car are not working well. No vehicle model comes with a warning light to signal a malfunctioned o2 sensor. Therefore, you have to rely on other signals to find out if the oxygen sensors are in perfect condition.

You can easily tell that your oxygen sensors need replacement if your fuel consumption per mileage has increased or you notice a check-engine light on the dashboard.

Bank 1 Vs Bank 2 Sensor

How to know if you should replace your Car Oxygen Sensors

There are many ways you can tell if your car needs a new oxygen sensor. When you see a check engine light on the dashboard, it could mean that there is a serious issue with your car that needs immediate fixing.

Your car catalytic converter could be overheating, or it could be a minor issue like a loose gas cap. It can also be signaling to you that you should replace the oxygen sensors or any faults on the car exhaust system.

If you drive to a mechanic shop, they can inspect your car and find out the reason your check engine light is on.

Other signs that you need to replace your car O2 sensors include:

  • Misfiring spark plugs.
  • Rough idle.
  • High gas emissions from the vehicle.
  • An increase in fuel usage per mile.
  • Your vehicle has covered over 60,000 miles.

Ideally, replacing your oxygen sensors plays a critical role in reducing the amount of fuel your car consumes by at least 40%. Take your vehicle through an emission test, if it fails, then it means there is o2 sensor problems, and you need to replace them immediately. A faulty oxygen sensor is a reason most vehicles have exhaust system issues.

Most vehicles come with emissions warranty that may determine when you are likely to replace your vehicle oxygen sensor. However, in most cases, the oxygen sensors will outlast the warranty.

Vehicle manufacturers recommend that if you have heated oxygen sensors (used in the 1980s and 1990s), you should replace them after covering 60,000 miles. If you are driving on a modern vehicle, you should replace the O2 sensors after covering at least 100, 000 miles.

The truth is that if you maintain your vehicle engine well, the oxygen sensors can last the lifetime of the vehicle. That is, you can cover over 250,000 miles before replacing the oxygen sensors.

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As your car ages, so does your oxygen sensors. Oxygen sensors degrade with time, depending on how you use fuel and how you maintain your vehicle engine.

Sulfur, an element found in crude oil, is responsible for the degradation of oxygen sensors. Therefore, when fueling your car, you should go for fuel with low sulfur concentration. Sulfur concentration in the fuel will determine directly how long the oxygen sensors are going to last.

Depending on the model of your vehicle, you can spend $100 or more to replace an oxygen sensor in your car engine. Also, you can spend more on labor, depending on the oxygen sensor location in the engine.

How to test Oxygen Sensors

Final Thoughts

It is always important to know your car engine parts because you can never tell when it will have issues. When you notice a check-engine light on the dashboard, it could be a red flag that something is wrong in the engine. If it’s the oxygen sensors that need fixing, you will have to identify the spoilt ones and replace them correctly.

Locate the faulty sensor using the two methods we have shared on this article and replace them to ensure your vehicle is safe on the road. If you are having trouble locating your bank 1, bank 2, or the O2 sensors in your vehicle engine, you should not hesitate to visit a certified mechanic shop for assistance.

Remember, timely repair of oxygen sensors can save you a lot of money and also effort.

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