Are you experiencing some weird symptoms with your car? Misfires here and there and overall poor engine work? And you diagnosed the code P0171 Ford? Well, if that is the case, then you are at the right place because there will be a lot to cover on this topic where we will learn about this trouble code and how to sort it out.
Having a problem like this can be really frustrating to deal with. Why I’m saying this? Well, because it is true. These types of codes are really difficult to diagnose and get right because they are only generic codes.
This means that you don’t get precise info about what could be wrong but you are left only to guess what could be the problem with your car. But still, it is not that difficult to diagnose them. Even though they can be misleading.
That’s why you need to upgrade your knowledge a bit and try to understand how the engine and its components work in a better way. You need to think like an engineer and you will sort out the problem really fast. And we are going to help you out with that.
First, we will cover the basics of car diagnostics and then we will cover the P0171 Ford and its meaning. Then we will go through the main causes of this code and also the symptoms that you will experience. After that, we will learn how to diagnose and sort the problem and lastly, we will learn how much it will cost. So, if you want to learn more, follow along.
Introduction To Car Diagnostics
Now before we cover the problem with the P0171 Ford code, let’s learn something more about car diagnostics in general. I bet there are not a lot of people that are reading this and do not know the basics of diagnostics. That’s why we need to make a proper introduction to the topic and learn these basic things before we move on to something more complex such as the P0171 code.
Nevertheless, car diagnostics is something that you need to know when trying to diagnose and fix a modern car that has some kind of problem that is hidden. But what type of problem is this?
Well, mainly the check engine light and other lights that turn on your dashboard. You just can’t know why these lights are there if you don’t do proper diagnostics.
And for this, you will need a tool also known as an OBD2 scanner tool. This OBD2 tool gives you access to the computer of the vehicle, also known as ECM or PCM.
This tool basically gives you access to this unit that controls everything and by doing this, you will get an extra good input on the problems that your car has. For almost every issue, there is a certain code. Some codes are generic, while some can be really specific.
The P0171 Ford code unfortunately is a generic trouble code that could mean a lot of things. But first, we need to define this code and its meaning. And in the following chapter, we are going to cover precisely that in detail.
P0171 System Too Lean Bank 1
Now as we covered the basics of car diagnostics, we can now move on to other topics and focus on the problem with the P0171 Ford code. We need to understand the meaning behind this code and what could be the cause for this code? Let’s elaborate.
First, let’s learn more about the definition of this code. So, what is the definition of this code? The simple definition for this code is “P0171 System Too Lean Bank 1”. But what does this mean?
Well, this means that the fuel to air mixture in your engine is not as it should be. More specifically on the first bank where cylinder number 1 is located. You probably run a V configuration engine since you received this type of code. So, the first bank is affected by this code.
The fuel to air mixture is just not right on this bank and there is too much air that gets inside of the engine and too little fuel. This is a lean condition, the opposite of the rich condition when there is too much fuel and too little air.
The right air to fuel mixture should be 14.7:1. This means that there should be 14.7 parts of air and 1 part of fuel. So, in your case, for example, there is a mixture of 16:1. Which is not good. And it could easily throw an error like this P0171 Ford and the check engine light.
That’s why you need to learn more about the causes of this error. You need to understand what could be causing this problem with your car. But before we do that, let’s cover the P0171 and P0174 codes and compare them. Because in some cases, you can get both of them.
P0171 And P0174
Now before we dive into the causes for the P0171 Ford code, let’s take a look at the P0171 and P0174 codes. So, why we are doing this?
Well, because these codes are pretty much the same. The definition for the P0174 code is “System Too Lean Bank 2”.
This means that the P0174 is telling you that you have a lean air to fuel mixture on the second bank. It’s mirroring the P0171 code.
The first one indicates a lean mixture on bank one where cylinder number one is located. While the latter indicates a lean mixture on bank 2 where cylinder number two is located.
So, since these two codes are basically mirroring. They have the same causes as well as the same symptoms. If you read this article, you can benefit and you will not have to do research specifically for that P0174 code.
Not to mention that the diagnosing process is the same for both codes. And sometimes they even show in pairs when there is an issue with the fuel system in general.
Something like a clogged fuel filter or bad fuel pump that doesn’t deliver enough fuel and leaves the mixture lean in the process. We are giving this just as an example of a scenario. Now let’s dive into the causes of the P0171 Ford code.
Causes For The P0171 Ford Code
Now as we cleared the basics of car diagnostics and learned what the P0171 Ford means, we can now dive into other topics and learn something more about the causes of this error.
As you probably know, everything happens for a reason. And so this P0171 code. Knowing the causes will tell you where to look and quickly sort out a problem like the one in our case. So, let’s begin.
1. Dirty Or Faulty MAF Sensor
The first and one of the most probable reasons for this situation With P0171 Ford is a problem with the MAF sensor. This MAF sensor is also known as a mass airflow sensor. It basically measures the flow of air into the engine.
It is located right before the throttle body on the intake hose. Without this filter, the air to fuel mixture could not be properly measured and balanced.
So, when this sensor gets clogged or possibly gets faulty, it will start to develop issues like the one with the P0171 Ford. A lot of Fords are having this issue because of this sensor alone, so you want to look for the problem here first.
2. Vacuum Leaks
The second probable cause for the P0171 Ford is the vacuum leaks. As you probably know, there are a ton of vacuum hoses and places from where you could get a leak on your car.
The intake manifold can crack and leak air. Then there are the intake manifold gaskets that also can dry out and allow leaks to appear.
Other systems include the PCV system which is the positive crankcase ventilation system. The EVAP system can leak as well. This is why you need to get some brake clean or carb clean and spray all these hoses and see if there is bubbling on the ones that go to bank 1. If there are bubbles, you know where to look. But more on this later on where we will diagnose the problem.
Also, check the throttle body and see if the flap works well. If it does not, then you will have to replace it or clean it if possible.
3. Weak Fuel Pump
The third most probable cause for the P0171 Ford is the situation with the fuel pump. If the fuel pump is weak, it will not send enough fuel pressure into the cylinders. Meaning that there will be less fuel than needed. So, you will have a problem like in our case.
In this case, there will be also another code that will be present. And that is the P0174. This means system too lean bank 2. This problem will basically occur in the two banks since both of them are going to be affected by this weak fuel pump.
So, if you get these two codes and some codes concerning the fuel pump. It might be worth giving it a check and replacing it if needed.
4. Clogged Fuel Filter
Another probability for the P0171 Ford is the clogged fuel filter. As you probably know, whenever this problem occurs. Especially when you get both codes P0171 and P0174, the main problem is often the fuel system.
More precisely the components that go from the fuel tank to the engine. These include the fuel pump, fuel filter, and fuel lines.
The fuel filter is the first thing that you want to check if you haven’t replaced it already. This filter can get really dirty and cause obstructions in the fuel delivery that will make the lean air to fuel mixture. So, beware of this component as well. In addition to this, you can also check the fuel pressure regulator as well.
5. Bad Oxygen Sensor Can Cause P0171 Ford
Another probable cause for the P0171 Ford that we would like to cover is a bad oxygen sensor also known as the O2 sensor.
This sensor is basically measuring the output gases in the exhaust. This sensor is one of the most important ones when it comes to determining the air to fuel mixture.
If this sensor is not performing as it should, it will trigger codes concerning it as well as codes that relate to the air to fuel mixture. Namely, the P0171 code if this happens on bank 1 or P0174 if this situation happens on bank 2 of the engine. Now let’s move to the last probable cause for the P0171 Ford.
6. Exhaust Leaks From The Exhaust Manifold
The last probable cause for the P0171 Ford that we would like to cover is the situation with the exhaust leaks.
Exhaust manifolds can leak or crack. On trucks especially, the bolts that hold these manifolds are exposed to salt, dirt, and whatnot during the winter. This causes deterioration of these bolts and the exhaust manifold starts to leak gases.
When there are leaks in the manifolds, the O2 sensor is not recording the information as it should. So, you might come across the P0171 code or something similar. That’s why when you have a problem that is affecting only bank 1. It is advised to check this exhaust manifold and the bolts in the process. Now let’s dive into the symptoms of the P0171 Ford.
Symptoms Of The P0171 Ford Code
Now as we covered the causes for the P0171 Ford, we can talk about the symptoms that this code also bears with it.
These symptoms really depend much on what is causing the issue in general. Now let’s elaborate on them before we learn how you can diagnose the problem.
1. Check Engine Light On
The first and most obvious symptom that you are already aware of is the check engine light. Whenever a problem like this with lean or rich air to fuel mixture there will be the check engine light on or flashing.
So, it is often advised to grab an OBD2 scanner and scan the car for codes. Make sure that you diagnose the problem and get the codes.
Along with the P0171 Ford, there will probably be other codes as well. Namely, the P0174 if this problem appears on bank 2. Also, see if there are codes for the MAF, O2 sensor, and other systems. These will be great leads to diagnosing the problem.
2. Engine Misfires
The second most probable symptom of the P0171 Ford is the frequent misfires that will be very common on bank 1.
The exhaust that is for bank 1 will be louder than the other. Some pops will be noticeable. The gas flow will be sort of interrupted by these misfires. But what are these misfires?
A misfire is a badly timed detonation inside of the cylinder. Either premature or delayed explosion. It is represented by ticks coming from the engine and the engine shaking often when working in these conditions. And when it comes to poor engine work, let’s cover the symptoms in the following chapter.
3. Poor Engine Work
Poor engine work will also be noticed when you have the P0171 Ford code. The engine will misfire as we mentioned previously.
There could be also a rough idle. The RPMs will fluctuate and will not be steady. This will also be followed by the slow response from the engine and lack of performance.
Whenever there is something like this, you can expect a significant drop in performance.
4. Blistered Or White Spark Plug Electrodes
And the last thing that we would like to cover when it comes to the P0171 Ford is the damage to the spark plugs.
When the air to fuel mixture is lean, there will be damage to the spark plugs. They will get all white and possibly will start to develop blisters on them. A spark plug check can tell you a lot of things, like in our case with the lean mixture. But how we can diagnose the problem? Let’s see next.
How To Diagnose And Fix The P0171 Ford F150 Code?
Now after we covered the causes and the symptoms of the P0171 Ford F150 code. Let’s dive into the diagnostics process and learn how we can diagnose this problem quickly and effectively.
The first thing you will need is to scan the car for codes. Make sure that you clear once all of them and scan them again. So, the ones that will stick are your problem.
If you get a P0171 Ford code only it means that you have a problem with bank 1. If you get both P0171 and P0174. It means that you have a problem with both banks. This means that the problem is often associated with the fuel delivery system.
In this case, you will need to check the fuel pump, fuel filter, fuel lines, and fuel pressure regulator. Since the problem is highly likely caused by these components.
If you only have the P0171, you will have to check the vacuum lines, the MAF sensor for that bank, the O2 sensor for that specific bank, and the exhaust manifold if there are leaks.
You can find leaks with a smoke machine. Or run the car and spray the areas that you suspect with brake cleaner or soapy water to see if there is bubbling that appears. Also, check the throttle body and give it a good clean with carb cleaner and remove the dirt on it. Make sure that it closes correctly.
Overall, that’s the diagnostic process. Fixing the issue depends on what component is faulty. The component will need to be repaired, cleaned, or replaced.
Cost To Fix P0171 Ford
So, what is the cost to fix this problem with the engine running lean on bank 1? Well, this depends much on the issue.
Some of the fixes are really simple, just clean off the throttle body and the MAF sensor. But some repairs can be rather expensive to do, like replacing a sensor.
Also, locating vacuum leaks can be really tricky if you don’t have a smoke machine. But a little bit of brake clean or carb clean can do the trick just fine as well.
P0171 Code Diagnosis: Symptoms, Costs, and Fixes
- P0171 is an OBD-II code that indicates that the fuel system on the first bank of the engine is weak, or a vacuum leak exists near this side of the engine, causing either too much oxygen or too little fuel in the exhaust.
- Possible causes of a P0171 code are a vacuum leak, weak fuel pump, broken fuel pressure regulator, blocked fuel filter, faulty powertrain control module, defective injectors, faulty oxygen sensors, clogged catalytic converter, and problems with the mass airflow sensor.
- Symptoms of code P0171 include a check engine light on or flashing, loss of power, rough at idle, misfiring or “coughing” engine, and white spark plug tips.
- Driving with a P0171 code is not recommended as it creates performance issues and might result in costly damage.
- Repairing a P0171 issue can range from $100 to $1,700 depending on the underlying issue.
- To diagnose the P0171 code, a mechanic can examine the engine for suction leaks using a vacuum gauge, inspect the fuel pressure sensor and the MAF sensor using a fuel pressure gauge, and test the mass airflow and oxygen sensors using the manufacturer’s technique.
- Common mistakes in P0171 code diagnosis are failing to look at technical service bulletins, which can save time and work.
- Possible fixes for a P0171 code include replacing the fuel pump or fuel filter, changing the fuel pressure regulator, replacing the powertrain control module, changing one or more injectors, replacing one or more oxygen sensors, changing the mass airflow sensor, and repairing the vacuum leaks.
- A dirty or defective MAF sensor, a clogged fuel filter, or a blocked air filter can also be responsible for the P0171 code.
- Although bad spark plugs or a bad gas cap are not common causes of a P0171 code, vacuum leakage downstream from the MAF sensor, a defective PCV valve, low fuel pressure, or dirty fuel injectors can potentially cause the P0171 error code.
Conclusion Of P0171 Ford
In this article, we have covered a lot when it comes to the P0171 Ford code. We learned what this code means in the first place. As we noted this is a situation when you have a lean air to fuel mixture on bank 1.
Then we have covered the causes and the symptoms of why it happens. In most cases, it is caused by a bad MAF sensor or vacuum leaks. But it can also be caused by other things as well.
Then we learned how you can diagnose the problem and lastly, we learned what will be the cost to fix the issue.
F.A.Q For P0171 Ford
Now let’s answer some frequently asked questions.
What Is P0171 Code For Ford
This is a trouble code that indicates that you have a problem with the lean air to fuel mixture on bank 1 of your engine. This means that there is too much air and too little fuel in the mixture. This could be attributed to a lot of things and a deeper diagnosis is essential to sort out the problem.
How To Fix P0171 Ford
Fixing this problem really depends on what is causing this code in the first place. Deeper troubleshooting on the MAF and O2 sensor needs to be done. As well as checking for vacuum leaks, the throttle body, and other things like the spark plugs, fuel system, etc.
This code means that you are running lean air to fuel mixture on bank 1 of your engine. This means that you have too much air in the mix and too little fuel. Deeper troubleshooting has to be done to determine what could be causing this issue.
This is a DTC trouble code that means that you have a lean air to fuel mixture on bank 2 of your engine. This means that there are too many parts of air and too little fuel. Deeper troubleshooting needs to be done to determine what could be the issue. But the main factors are the MAF sensor, O2 sensor, throttle body, vacuum leaks, and fuel system.
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