Bank 2 Sensor 1 Upstream Or Downstream

Bank 2 Sensor 1 Upstream Or Downstream – Which One Is It?

Are you having a problem with the O2 sensor and you are asking yourself the question of bank 2 sensor 1 upstream or downstream? Well, if that is the case, then you are at the right place because there will be quite a lot to cover on this topic.

Doing the proper research before you do a repair is key in some aspects. You need to learn some things before you decide on doing some expensive repairs like an O2 sensor replacement. You just have to know which is the upstream and which one is the downstream sensor.

There are a ton of people that confuse these two and make mistakes and replace the wrong one. And this type of mistake I would not recommend you to do since it is quite expensive. This is why we are going to teach you everything you need to know when it comes to these types of sensors and also how to replace them.

First, we are going to learn what is an O2 sensor and how it works. Then we will cover the bank 2 sensor 1 location. Then we will learn if bank 2 sensor 1 upstream or downstream. We will cover this in-depth. As well as the trouble codes that often appear on this sensor. And also the upstream O2 sensor symptoms. After that, we will move into diagnosing stuff and learn how you can replace this sensor and at what cost. So, if you want to learn more, follow along.

What Is An O2 Sensor

Now before we dive into bank 2 sensor 1 upstream or downstream and learn more about the location. Let’s cover some of the basics when it comes to the O2 sensor, and learn more about how it looks and its basic mode of operation. There are a ton of people reading this article who are not familiarized with these components, so this will be a really nice introduction to the topic for them.

So, what is an O2 sensor? The name itself should associate you with something. O2 as we all know is the chemical element known as oxygen. This is one of the most abundant elements on the planet earth along with helium and hydrogen. And also the third most abundant element in the whole universe.

But we are not here for chemistry lessons, we are here to understand more about the O2 sensor. Why is it called this way?

Well, this sensor is there to measure the oxygen levels in the system. And then to help the computer adjust the air to fuel ratio inside of the combustion process.

This sensor is also known as the lambda sensor in some parts of the world. It was patented by Bosch in the 1960s and since the late 80s and early 90s is one of the irreplaceable components in any automobile out there.

In each car, there are at least two of these sensors. One before and one after the catalytic converter. But bank 2 sensor 1 upstream or downstream? Well, the answer to these questions we are going to elaborate on later in the article. Now let’s take a look at how this sensor works behind the curtain.

How Does An O2 Sensor Work

Now since we introduced ourselves to the O2 sensor and learned a little bit about it. We think that before we start discussing more about bank 2 sensor 1 upstream or downstream, it is time to learn more about how the O2 sensor works in reality.

The O2 sensor is just like a probe, it is screwed on the exhaust and the sensing element is exposed to what is happening in the exhaust pipe.

Inside every O2 sensor, there is a heating element. This heating element allows the sensor to get up to temperature much quicker and is quite an essential component of the sensor. This component that works independently of the sensor but is built inside of the sensor housing often tends to fail and cause problems.

The sensing element itself is made out of very expensive metals such as platinum. There is also a ceramic coating around the sensing element that is designed to keep the sensing element in good health and absorb all of the heat that is found inside of the sensor itself.

Nevertheless, the sensor is connected on the other side to the wiring harness and directly communicates with the PCM, which is the Powertrain Control Module.

And this sensor plays a big role when it comes to the proper work of the engine. It helps when it comes to adjusting the air-to-fuel ratio, as well as helps with the proper work of the catalytic converter.

So, when this O2 sensor does not function well, you could face problems with the catalytic converter as well as problems with a rich or lean air-to-fuel mixture. But what about bank 1 sensor 2 upstream or downstream? More on that in a moment.

Bank 2 Sensor 1 Location

Now let’s learn more about bank 2 sensor 1 location before we dive into bank 2 sensor 1 upstream or downstream. Where is this sensor located?

Well, as we mentioned in the previous chapters, in order to get a proper reading and read the exhaust gases, the sensor has to be mounted on the exhaust.

This means that there is a factory nut installed on the exhaust that allows these O2 sensors to be bolted onto and then read the exhaust gases properly.

Each vehicle, has at least two sensors, one of them is before the catalytic converter and the other one is after the catalytic converter.

Having two of them is really essential if you want to get a proper reading and your catalytic converter to work as it should. So, where is the bank 2 sensor 1 location?

Well, when you have bank 2, this means that you are running a V-configuration engine. A V6 or a V8.

So, one side of the engine is bank 1, and the other side is bank 2. The side where cylinder number 1 is located in bank 1, while the side where cylinder number 2 is located in bank 2.

Finding which side is bank 1 and which one is bank 2 can be rather a challenge. Usually, on the side of the block, there is a stamp with the number 1 where bank 1 is located. Then you know that on the opposite side is bank 2.

Then you know that sensor 1 is the first sensor. In other words, the sensor that is found before the catalytic converter on the bank 2 side of the engine. But is bank 2 sensor 1 upstream or downstream? More on that, next.

Bank 2 Sensor 1 Upstream Or Downstream

Now let’s move on to the main topic and learn more about bank 2 sensor 1 upstream or downstream. Is this sensor upstream or downstream? Well, let us explain.

As we noted previously, there are two O2 sensors per bank. Inline engines have only two of them while V-engines have four of these sensors. Two per bank.

So, on bank 2 you have two sensors. One is upstream and the second sensor is the downstream sensor. So, which one of these is upstream and which one is downstream?

The correct answer is that sensor 1 is always upstream and sensor 2 is downstream. The name is self-explanatory.

Mainly because the exhaust is designed in such a way that the gases flow downward. So, the upper sensor is always sensor number 1 and the downstream sensor which is at the bottom is sensor number 2.

There are plenty of diagrams that will allow you to figure out how to find them and also which is which. So, be sure to check some diagrams, and seeing them for yourself is always a good thing to visualize things and get a much better perspective.

So, we learned bank 2 sensor 1 upstream or downstream and we know that this sensor is upstream. Now let’s take a look at the difference between these two sensors and how they differentiate.

Upstream VS Downstream O2 Sensor

Since we covered bank 2 sensor 1 upstream or downstream, let’s now take a look at the difference between these two sensors. Why is this necessary?

Well, a lot of people are confusing these two sensors are thinking that they are interchangeable. Which is actually not the case. Even though they are both O2 sensors, they have different purposes. So, what is the difference?

Well, bank 2 sensor 1 is the upstream sensor as we mentioned. This sensor is also known as the air-to-fuel ratio sensor and is mounted before the catalytic converter.

This sensor helps in determining the right air-to-fuel ratio. So, the engine works well and doesn’t have any problems.

While bank 2 sensor 2 is the downstream sensor. This sensor is not particularly focused on the air-to-fuel mixture but more on the proper operation of the catalytic converter.

The downstream sensor is reading the emissions after the catalytic converter and makes sure that the catalytic converter works well. Or if it doesn’t, you will get a P0420 code. So, you get the idea. But what are the most common codes for the bank 2 sensor 1? Let’s find out next.

Bank 2 Sensor 1 Code

Now since we learned bank 2 sensor 1 upstream or downstream and we confirmed that this is an upstream sensor. We think that now it is time to dive into the trouble codes that you will notice whenever this sensor malfunctions.

As you are probably aware, when a certain sensor is bad, there will be the check engine light on the cluster as well as the trouble codes once you started diving deeper into diagnosing the matter. So, what are the trouble codes concerning this particular sensor?

Well, there are a few of these codes that could appear. The first is the P0150 which indicates circuit malfunction. Then there is the P0151, which indicates a low circuit voltage, P0152 indicates high circuit voltage, P0153 means slow circuit response, P0154 means that there is no circuit activity, and the last is the P0155 which means that there is a heater circuit malfunction.

As we noted in the previous chapters, the heater element often tends to fail and cause codes. So, the P0155 is probably one of the most common codes. But what are the other symptoms concerning the upstream sensor since we learned if bank 2 sensor 1 upstream or downstream? More on that, next.

Upstream O2 Sensor Symptoms

We learned about bank 2 sensor 1 upstream or downstream and learned that this sensor is upstream, let’s now focus on the main symptoms that are associated with the upstream O2 sensor. What symptoms can you expect?

We have covered the check engine light before and the trouble codes. So, we will not put big attention to this symptom in the following chapters in order not to repeat ourselves. Let’s now cover the other symptoms of a bad O2 sensor.

Bank 2 Sensor 1 Upstream Or Downstream, Symptoms #1: Rough Idle

So, we covered about bank 2 sensor 1 upstream or downstream and learned that this is the upstream sensor. So, what is the first symptom associated with this sensor?

Well, the most common symptom with this sensor is the rough idle. So, what is a rough idle? A rough idle is a situation when the engine is not happy when is idling.

Bank 2 Sensor 1 Upstream Or Downstream

You will notice how the engine runs poorly instead of running smoothly at 800 RPM. The RPM will fluctuate and drop in some cases.

So, when you notice something like this, you know that it is either MAF, MAP, O2, sensor, spark plug, or coil issue. This is why we recommend checking all these components. Now let’s move on to the next symptom.

Bank 2 Sensor 1 Upstream Or Downstream, Symptoms #2: A Drop In Fuel Efficiency

The next symptom in our list since we covered bank 2 sensor 1 upstream or downstream is the drop in fuel efficiency.

Whenever the upstream O2 sensor is not working as it should be working, you will face a ton of problems. More precisely, the fuel efficiency will increase.

This will be the case because the computer is not able to calculate the air-to-fuel ratio correctly since your sensor is not working well. And will cause the engine to use more fuel than it actually needs and cause a significant drop in fuel economy. So, if you have a big dip in fuel economy, make sure that you sort this problem promptly before it becomes even bigger.

Bank 2 Sensor 1 Upstream Or Downstream, Symptoms #3: Failing The Emissions Test

The second common symptom associated with a bad bank 2 sensor 1 upstream is failing the emissions testing.

When this sensor is not working, your car will not produce the same amount of emissions on bank 1 and bank 2.

So, bank 2 will pollute quite a bit more. And if you take a vehicle like this to the inspection, you will highly likely not going to pass.

The car emissions will be through the roof and will hurt the emission performance of the vehicle. This is why you will need to fix the car, then bring it back to test it again with the new O2 sensor. Now let’s move on to the next symptom since we covered bank 2 sensor 1 upstream or downstream.

Bank 2 Sensor 1 Upstream Or Downstream, Symptoms #4: Black Smoke From Exhaust

The next symptom that we are going to discuss when it comes to bank 2 sensor 1 is the black exhaust smoke coming from the tail pipe.

Bank 2 Sensor 1 Upstream Or Downstream

You will notice how this symptom gets more and more pronounced. So, why is this the case? Well, this is the case mainly because your car is running rich.

The air-to-fuel mixture is not properly adjusted by the PCM because it is missing the data from the bank 2 sensor 1. And since this is the case, it will cause the engine to run rich on bank 1 and the car will burn more fuel and will release black smoke and the smoke will smell like unburnt gasoline. So, beware of this symptom.

Bank 2 Sensor 1 Upstream Or Downstream, Symptoms #5: Broken Catalytic Converter

And the last symptom of bank 2 sensor 1 upstream or downstream is the broken catalytic converter. If the sensor is broken and your car is running rich, you can expect it to spoil your catalytic converter as well.

This unburnt fuel will simply clog up the catalytic converter and will prevent the gases from flowing. And once this happens the car will lose power and will be struggling to run.

So, whenever you have a bad O2 sensor, it is important to diagnose and sort out the problem quickly. Luckily for you, we are going to elaborate on how this is done right in the following chapter.

Diagnosing A Bad O2 Sensor

So, we learned more about the bank 2 sensor 1 upstream or downstream. And we learned that this is the upstream sensor that is bad. So, how you can diagnose this component on your vehicle?

Well, the first thing that you will need to do is to grab an OBD2 scanner device. You will need a scanner to get to the codes that the PCM is recording.

So, scan the car and if you have codes ranging from P0150 to P0155, then you know that something with the sensor is bad. There could be high or low voltage, no voltage, or the heater element could be bad.

Sometimes if you suspect that the sensor is good, it is advisable that you check on the wires and see if the connectors are good and not rusted out. Sometimes wires can be melted. So, doing this in advance will guarantee that you don’t pay a ton of money for a new sensor.

You can also bench test this sensor with a blow torch and a multimeter. How you can do this is by can checking in the video that we attached above where this process of testing bank 2 sensor 1 upstream or downstream is explained in-depth. Now let’s move on to the costs that are involved in replacing this sensor.

Cost To Replace O2 Sensor

So, we learned more about bank 2 sensor 1 upstream or downstream and learned that this is the upstream O2 sensor.

Now let’s take a look at how much it will cost you to replace the O2 sensor. Well, this sensor on average costs between $150 to $250 for the part alone. Labor will also cost you $100 to $250. So, the average cost will probably be about $400 to $500 to replace this component at a shop. If you do things by yourself, you will only pay for the parts alone.

Bank 2 Sensor 1 Upstream Or Downstream: In Conclusion…

In this article, we have covered quite a bit when it comes to the topic of O2 sensors. First, we learned what is an O2 sensor and how it works. Then we covered bank 2 sensor 2 upstream or downstream and learned that this is an upstream sensor and we also learned where it is located.

After, we covered the symptoms that are associated with this component and learned that there are a few of them. Lastly, we learned how to diagnose a bad upstream sensor and how to test it the right way.

FAQs On Bank 2 Sensor 1 Upstream Or Downstream

Now let’s answer some frequently asked questions.

What Does An O2 Sensor Do

The O2 sensor is a simple probe that is measuring the level of oxygen inside the exhaust pipe. This component helps the engine to adjust the air-to-fuel ratio as well as measure the work of the catalytic converter.

Where Is The O2 Sensor Located

The O2 sensor is located on the exhaust system. There is one sensor before the catalytic converter and one O2 sensor after the catalytic converter.

Where Is The Bank 2 Sensor 1 Located

This sensor is located on bank 2. This is the bank of the engine where cylinder number 2 is located. Sensor one is the first sensor that you will notice before the catalytic converter.

How Many O2 Sensors Are In A Car

The number of sensors depends on the engine. Inline engines have two of these sensors. While V-engines have four of them. Since they have two banks, bank 1 and bank 2.

What Does A Bad O2 Sensor Look Like

Visually, there is no difference between a good and a bad sensor. The difference is in the performance and the symptoms that the bad one is producing. Namely, check engine light, rough idle, black exhaust smell, and bad fuel economy.

Approved Tools

These tools have been tried and tested by our team, they are ideal for fixing your car at home.

Leave a Reply

Your email address will not be published. Required fields are marked *