Is your car working strangely lately? You decided to scan the car for codes using your OBD2 scanner and you found out that it has a P0171 code that means the system too lean bank 1? What does this system too lean bank 1 mean?
Check engine lights can be one of the most annoying things that could happen to any driver. You don’t know what they mean until you decide to scan the car for codes. This can cause delays until the problem becomes bigger and bigger.
Scanning the car for codes is probably the best idea in these situations. It is very useful to have a code reader and scan the car by yourself. By doing this, you can get first-hand input on what is going on inside of your car. In doing so, it will save you thousands on mechanics that often misdiagnose cars, and you will not have to pay a lot of cash to fix problems that do not exist.
Also, scanning your car by yourself is going to give you plenty of first-hand experience in dealing with problems. Plus, you will improve your troubleshooting skills. Troubleshooting is a science by itself and finding out that the system too lean bank 1 problem exists makes this an easier issue to overcome. For this, we are going to help you out.
In this article, we are going to learn everything about the P0171 code. We’ll start from the basics, and then we will move to the symptoms and the probable causes for this issue and how to solve them. So, let’s dive into it.
What Is System Too Lean Bank 1 Problem?
The system too lean bank 1 or code P0171 problem means that there is lean fuel to air mixture on the first bank of your engine. This bank is where cylinder number 1 is located, that’s why in the error message it says bank number 1.
But to get this message, you need to have a check engine light and scan the car for codes. Check engine light can mean a lot of things and that’s why scanning is a must.
Scanning the car can be done in two ways. One is by visiting a workshop and you paying for the service of diagnosing the issue. Or, you can try diagnosing the problem by yourself with an OBD2 scanner tool. These scanner tools are fairly cheap and can be found anywhere online and in most car parts stores for $30. But, I would recommend a better scanner if you want to diagnose issues in-depth and have better input and not have to google the errors online.
After scanning the car if you have this issue, you are going to get the error P0171. If you look online for this error, you are going to find out that it means that the system too lean bank 1. But what does this mean?
This means that there is too much air sucked inside the bank 1 cylinder and the fuel to air mixture is completely off, they need to be addressed quickly.
The air needs to be 14.7 parts to 1 part of fuel. If the air ratio is above 14.7, the PCM is triggered and it dumps more fuel inside of the cylinder. This extra fuel makes the car develop symptoms and also throw a check engine light. And we are going to discuss that in the next chapter.
What Are The Symptoms Of System Too Lean Bank 1?
As we said, when the air to fuel mixture is not 14.7 to 1, it means that some symptoms are going to develop. That’s since the PCM is telling the injectors to dump more fuel into the combustion chamber. This extra fuel is going to cause all sorts of issues with your engine, and the running of the engine is not going to be something that you will enjoy. So, what are the symptoms when you have a system too lean bank 1 problem? Let’s find out.
Check Engine Light On
One of the first symptoms of this problem is the check engine light. This check engine light can be pretty annoying and you are probably will not enjoy it when you see it on your dash.
But the check engine light is there for a reason, and that is to inform you that there is something wrong with your engine. This check engine light makes diagnosing problems on your vehicle a breeze.
You just plug in your OBD2 scanner into the port and scan the car for codes. After the scan, you can look for the codes and learn more about them. Without removing anything at all, you have the answers to your questions just one click away.
Specifically for this problem, you are probably going to get an error code of P0171 that means the system too lean bank 1. This means that the air to fuel mixture is messed up, and you need to troubleshoot some of the components that we are going to cover later in the article.
Low Engine Power
Another symptom of the system too lean bank 1 problem is the low engine power. This is the case because there is too much air into the cylinder that is sucked in from the intake.
All this extra air could not be properly ignited per one revolution of the engine. Therefore, this extra air is pushed into the exhaust.
Your engine would not like this. Low combustion means a lack of power from the engine. The lack of power will ruin your car’s performance and you will get a check engine light as we mentioned above.
This loss of power can be a frustrating thing, especially if your car already has a low-powered engine. If this affects you, your car would barely move on the road.
That’s why addressing this issue as soon as possible is going to solve your problem in the long run. In one of the next chapters, we are going to learn what could be the possible culprits for this problem, and how you can overcome this issue. But first, let’s discuss the next symptom and that is the rough idle of the engine that comes with the low engine power.
Another symptom that comes along with the low engine power is the rough idle. This rough idle is a clear indication that you are having a problem with your ignition system. More specifically, with the issue of the system too lean bank 1 problem.
You will notice rough the engine idle is when you start the car. You will see how the needle on the tachometer is moving up and down. This uncontrollable movement is not a good sign. This movement means that something in the combustion process is not right and needs checking.
When you are experiencing a problem like this, the best thing to do is to open up the throttle body and see its condition. If it’s full of gunk, then you can give it a good clean. If this doesn’t help, it means that there is something wrong with the sensors. We are going to discuss that in one of the next chapters when we are going to cover the possible culprits for this problem.
Engine Trying To Stall
When you are having a rough idle, the engine as well is going to try to stall sometimes. This can be most pronounced when you remove your foot from the gas pedal.
Removing the foot from the gas pedal will cause too much air to be consumed on one of the banks of the engine, and this can result in low combustion on bank 1.
In this situation, the best thing you can do is applying your foot on the throttle more often. This will result in balancing the air to fuel mixture and the engine will keep on working. But it can happen where you forget to apply the gas, and this is going to result in engine stalling.
So, if you are experiencing an issue like this, the best thing you can do is diagnosing the problem with a code reader and see what is the real issue and then find the real culprit.
We are going to discuss all the probable reasons after we cover all the symptoms of the system too lean bank 1 problem.
Increased Fuel Consumption
Increased fuel consumption will also be one of the symptoms if you are having a system too lean bank 1 problem.
This is the case because there is too much air in the mixture and the engine is trying to stall all the time. Thus, you are balancing this by applying your foot on the gas pedal. Applying more gas means that more gas than is necessary is injected into the cylinder.
This extra gas is going to worsen your fuel mileage. If you have an issue like this then, you can expect that your fuel mileage is going to drop by around 5 mpg in the worst case. Should you drive your car as it is for a long time, it can hurt your wallet.
If you notice how the car becomes thirstier, it’s a clear sign that something has to be checked and repaired. By doing so, you will fix the problem and not waste so much money on gas.
The only way to do so is by scanning the car for codes. This is to see what is causing this problem to appear in the first place. If you get the problem of the system too lean bank 1 issue, then read till the end because we are going to uncover all the possible culprits for this problem.
Engine misfires as well can be one of the possibilities when you are experiencing a system too lean bank 1 problem on your car.
Imagine that there is too much air into the cylinders, and this air is not ignited. This is going to result in engine misfires. Basically, the valves will not work properly and will be open for too long until they remove all the unburnt air from the combustion chamber.
These misfires are subtle and not everyone can notice them. Also, they are caused by other culprits as well, such as bad spark plugs or bad coils. Rich air to fuel mixture as well can cause these misfires to appear.
So, scanning the car for codes is going to answer all of your questions. And if the answer is the system too lean bank 1, then you know that your cylinders on bank 1 are running on a lean air to fuel mixture. But what are the causes for this lean air to fuel mixture? Well, we are going to discuss that next, and see how you can solve this problem quickly and effectively.
What Are The Causes For This Problem
There are many causes that can prompt the system too lean bank 1 problem to appear. And, in this chapter, we are going to cover all of them. This is for you to have a better idea of what could go wrong with your engine.
Bad Or Clogged Mass Airflow Sensor
The mass airflow sensor is one of the first things that you need to check when you get this error with the system too lean bank 1 problem.
This problem often happens because of a dirty MAF sensor that is located on the intake. If you are in this situation, the best thing is to remove the sensor from its position and give it a good cleaning.
After you clean the sensor, you can place the sensor back in its position. This, hopefully, is going to solve your problem. If not, you need to test your MAF sensor and see if it’s faulty. If it’s faulty, then the sensor needs replacing with a new one. And what about the costs? We are going to cover them later in this article.
Vacuum Leaks, Intake Manifold Gasket, PCV Valve Hoses
Another culprit for this problem can be vacuum leaks. These vacuum leaks are the hoses from the PCV valve and the EVAP system.
When the PCV valve and the EVAP solenoid fail, they allow too much air to be inserted into the engine. This results in problems like this with the system too lean bank 1 problem to appear. In this case, the best thing to do is to check the PCV valve and the EVAP solenoid and see if they are in proper working order.
If some of these components are not good, then you will have to replace them with a new one. They are cheap and readily available at almost any parts store.
Another thing to check is the hoses if they are leaking, and also the gasket on the intake manifold. If the gasket on the intake manifold is too old, then replacing it with a new one will be a good idea. They are fairly cheap and readily available as well as vacuum hoses.
Bad Fuel Pump
A bad fuel pump can also be the cause for the system too lean bank 1 problem. This is the case because the fuel pump is not sending enough fuel into the cylinders. In this case, there is too much air in the engine and there is a lack of fuel inside. That’s why a lean air to fuel mixture can appear and ruin your engine performance.
You can test your fuel pump very easily. When you put your key on the ignition you should hear a click from the back. If there is no click, it means that your fuel pump is not engaging. In this situation, replacing the fuel pump will be the only solution for you and your problem with the system too lean bank 1 error.
Clogged Fuel Filter
A clogged fuel filter can also cause a lack of fuel in the engine. If the fuel filter is clogged, you basically will be left with little or no fuel in the fuel line that goes from the filter to the engine.
And this is going to result in lean air to fuel mixture and possible problems like the check engine light and the code for the system too lean bank 1 problem to appear.
Bad Fuel Injectors
Bad or clogged fuel injectors can also be one of the culprits for this specific problem with the lean air to fuel mixture.
This is the case because the fuel injectors do not inject the right amount of fuel if they are clogged. This will result in low fuel being sent to the combustion chamber. This means that the air to fuel mixture will be unbalanced and the check engine light may come on the dashboard.
Broken O2 Sensor
O2 sensors as well can be one of the primary suspects when there is lean air to fuel mixture in the engine. This is the case because the O2 sensors are located in the exhaust. These sensors are measuring the exhaust gasses that come out.
Then, based on this measuring, the PCM decides how much air and fuel to drop inside of the cylinders. Bad readings from these O2 sensors can lead to bad air to fuel mixture and possible system too lean bank 1 error.
O2 sensors can be tricky to test because you need to remove the sensor, and you will need a blow torch and a multimeter to perform this work.
Cost To Fix This Problem – System Too Lean Bank 1
The cost to fix this problem depends on the component that is faulty in your system. For example, if the mass airflow sensor is damaged, you can expect to pay a hefty price of $200 for a new part. This is the case because the MAF sensors are relatively expensive and cost a lot.
If you have a faulty fuel pump, you can also expect to pay more than $200 for a new unit. Injectors and fuel filters, on the other hand, are fairly inexpensive and can be found for less than $50.
Also, if the problem is caused by a vacuum leak, you can expect to pay less money to solve these issues. This is since a PCV valve or an EVAP solenoid is only $15 to $30 to replace.
Another factor is the labor cost. Parts are cheap, but the labor can be pricey since most of the shops demand high hourly wages and these wages are between $50 to $100 per hour on average.
So, the price can add up and for simple problems like this, you can pay a hefty price. But if you decide to perform DIY work on your car, you can save money on the labor and also learn some things about cars. On top of that, you can become proficient when it comes to mechanics and mechanical issues. That’s especially in troubleshooting. If you are a good troubleshooter, you can diagnose any problem easily.
Diagnostics Mistake When It Comes To System Too Lean Bank 1
Many people when they get the problem with the system too lean bank 1 decide to replace the O2 sensor since they get a bad reading but you shouldn’t hurry with the diagnostics.
Test other components as well because you never know where the problem lies. The first things that you need to focus on are the MAF sensor and the vacuum hoses. Once these things are deemed good, you can move on.
I’m saying this because a new O2 sensor is fairly expensive, and if you replace it by mistake you will waste your money.
Conclusion – System Too Lean Bank 1
In this article, we have covered a lot when it comes to the problem with the system too lean bank 1. We learned that this problem happens on bank number one and it happens because the air to fuel mixture is too lean.
We understood that you can experience symptoms like misfires, rough engine work, low engine power, increased fuel consumption. All these symptoms indicate a problem. But what about the culprits?
The main culprits for this issue are the mass airflow sensor and the vacuum leaks. Other things that can cause this problem are the bad O2 sensor, bad fuel system components like the fuel pump, fuel filter and injectors also can cause this problem to appear.
The most important thing is to not rush with replacing the components. Also, carefully test them before you decide on your next step.
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