P0171 Honda Accord – How To Diagnose This Problem?

P0171 Honda Accord – How To Diagnose This Problem?

August 22, 2022 0 By CarGuy

Have you gotten the check engine light and you found out that you have the P0171 Honda Accord code? 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 are going to cover everything when it comes to the meaning, causes, and symptoms that this code causes.

Troubleshooting is true mastery and you should be one of those guys who want to learn how to do it. Modern cars are very complex and if you learn how to troubleshoot, you will have that extra edge when it comes to diagnosing problems in your vehicle.

Problems, which can be rather expensive to fix if you are asking me. Imagine that you go to a shop with very unskilled mechanics and they tell you to change ten parts before they finally get the problem right. This costs time and money, and you definitely don’t want to lose your time and money with incompetent people. This is why you need to learn how to troubleshoot and we are going to help you out.

First, we are going to learn what is car diagnostics, and then we will cover the P0171 Honda Accord meaning. We will learn why this code appears. In other words, we will cover the causes, as well as the symptoms that it could trigger. And then we will take a look at how you can diagnose and sort out the problem. So, if you want to learn more, follow along.

Introduction To Car Diagnostics

Now before we dive into more complex topics like the P0171 Honda Accord, let’s first take a look at car diagnostics in general and learn more about how this procedure is taken. What are the methods and tools used? Since if you want to be a proper modern mechanic, you need to figure this stuff out. So, let’s cover this topic briefly.

Modern cars are not like the cars back in the day. Back in the day, things were a lot simpler, and problem-solving was also quite easier since there were no complex electronics and sensors all over the vehicle that regulate everything on the car.

So, old-school mechanics relied a lot on their experience. Not that modern mechanics do not. But modern mechanics more rely on some tools. More precisely, the OBD2 scanners and also multimeter tools. Why is this the case?

Well, this is the case because modern cars include a computer that regulates everything. This computer is known as PCM, ECM, or ECU. But it is the same thing. This is the main computer that regulates all the sensors and gets a reading from these components. If there are too many red flags, it will trigger the check engine light. And like in our case, the P0171 Honda Accord code.

But in order to get this code, you will need to access the PCM with an OBD2 scanner tool. With this tool, you will be able to scan the car for codes and see if there are any problems in the system.

Then once you’ve diagnosed the problem, you can move on and learn more about the component. And for this, you will need to get a multimeter to measure the properties of the specific sensor.

P0171 Honda Accord Meaning

Now since we learned the basics of car diagnostics, we can move on to other topics. Namely, the P0171 Honda Accord meaning. What does this P0171 code mean in the first place?

The simplest definition for the P0171 code is “Bank 1 Has Too Much Air And Not Enough Fuel”. So, what does this means in the first place?

Well, this means that the engine is running lean. But what does lean means? In order to understand this problem in detail, we need to understand the proper air-to-fuel mixture.

A proper air-to-fuel mixture is 14.7:1. This means that in the mixture you need to have 14.7 grams of air per one gram of fuel.

So, what happens in this case, is the air mix either is above 14.7 or the fuel is below 1. And in this situation, you get a lean state.

On the contrary, when you have more parts fuel and little parts of air, is considered to be a rich state. In other words, your car is running rich.

What is worth noting is that both of these conditions are detrimental to your engine as well as to your budget. Since the air-to-fuel mixture is bad, there could be a lot of expensive problems that could arise if you decide to run the engine like this for a long time.

So, this is why it is really crucial that you dive into solving the P0171 Honda Accord code and make sure that this problem does not become worse and more problems arise. But you shouldn’t worry because we are going to help you out. First, we will take a look at the possible causes for the P0171 Honda code and then we will cover the P0171 Honda symptoms.

P0171 Honda Accord Causes

As we learned more about the P0171 Honda Accord meaning, we can move on and cover some of the causes. We need to understand why this problem appears in the first place.

There are a number of causes and this is why we are going to list them in the following chapters and elaborate more on them in-depth and understand why this P0171 code problem appears.

1. Bad MAF Sensor

Now let’s start with the first reason for the P0171 Honda CR-V. And that is the bad MAF sensor. If you probably are familiar with sensors, you know that the MAF sensor is the Mass Airflow Sensor.

This sensor basically measures the air that goes into the intake of the car. This sensor is pretty essential because it basically tells the car how to adjust the air-to-fuel ratio. If the sensor is bad and does not register the amount of air in the system, problems like the P0171 Honda Accord will occur. So, make sure that this is one of the things that you address first.

2. Bad MAP Sensor

The second most common reason for the P0171 code Chevy is probably the bad MAP sensor. But what is a MAP sensor?

Well, a MAP sensor is Manifold Absolute Pressure Sensor. But what does this mean? Well, this sensor simply monitors the pressure in the intake manifold and helps in determining the air-to-fuel mixture.

In the beginning, all cars had MAP sensors. But the MAF replaced the MAP sensor in recent years. Still, MAP sensors are used in combination with the MAF on turbocharged petrol or diesel engines.

So, if your engine has a turbo, then you probably have a MAP sensor as well. Nevertheless, when this sensor fails, it could cause problems like these with the check engine light and the code P0171 Nissan or P0171 Honda Accord. Now let’s move on to the next probable cause for this problem.

3. Vacuum Leaks

The next cause for the P0171 Honda Accord that we would like to cover is the problem with the vacuum leaks.

If you didn’t know, when it comes to cars, everything has to be vacuum tight inside of the engine. So, the intake manifold should be perfectly tightened and no unmetered air should get in.

And what can happen is sometimes the gaskets that are holding the intake can fail and allow unmetered air to enter the combustion. And you could end up in this situation.

On top of this, the engine intake manifold could crack and also allow air to enter the engine. Modern intake manifolds are made out of cheap plastic that could crack and cause this issue.

On top of this, systems like the PCV and the EVAP system that are in charge of gas recirculation can also cause problems like these. So, it is a good idea to test them with a smoke machine and determine whether they are the reason for the P0171 Honda Civic code.

4. Weak Fuel Pump

The next common cause for issues like this with the P0171 Ford is fuel delivery issues. Fuel delivery issues can become a big problem.

Especially if we are talking about a bad fuel pump. If the fuel pump does not have enough power to push the fuel into the engine, you will have a lean air-to-fuel mixture. Which means too much air and too little fuel.

So, the fuel pump is the one that you need to make sure is in good health when it comes to sorting out the P0171 Honda Accord.

5. Clogged Fuel Filter

The next, also very common cause of a P0171 Honda Accord problem is the clogged fuel filter. A lot of people are forgetting that replacing the fuel filter is considered to be regular maintenance and these filters should be replaced every 30,000 miles.

Because if you don’t do this service on your car, problems like these could happen. The fuel will not be able to pass through the filter and you will end up with a lean condition inside of the engine. Resulting in a P0171 Honda Civic code. Now let’s move on to the next most common cause of this problem.

6. Clogged Fuel Injectors

The next probable cause for the P0171 code that we are going to cover connected to the fuel system is the situation with the fuel injectors.
The fuel injectors can also get clogged up and cause problems like this. The lack of fuel in the system will cause the car to run lean and you could face some struggles like the check engine light and the P0171 Dodge code.

So, whenever you notice something like this, it is really useful to check the fuel system as well as the injectors. Just to make sure that nothing of this is causing the problems. Now let’s move on to the last symptoms.

7. Exhaust Leaks

And the last two symptoms concerning this problem with the P0171 Acura are the problems with the exhaust. More precisely, exhaust leaks.

Exhaust leaks can appear before the O2 sensor and these leaks could cause the O2 sensor not to read properly. So, this could make the car run lean or rich.

These exhaust leaks are usually manifold leaks. Either caused by a cracked exhaust manifold or possibly by broken exhaust manifold bolts that cause this leak to happen and trigger the check engine light with the P0171 code.

8. Bad O2 Sensor

And the last probable cause for the P0171 Honda Accord problem that we are going to cover for today is the O2 sensor. Also known as air to fuel ratio sensor on older cars.

This sensor works with the MAF and MAP sensors and together adjusts the air-to-fuel ratio. As we noted previously, the MAP and MAF are mounted on the intake and before the intake, respectively, while the O2 sensor is mounted on the exhaust.

In fact, there are two O2 sensors, one is the upstream and one downstream sensor. One before the catalytic converter, and one after the catalytic converter. Inline engines have two of these sensors while V6 or V8 engines have four O2 sensors.

And when one of these sensors fails, it could cause problems. Namely, the P0171 Chevy or P0171 Honda Accord, depending much on what model of a vehicle you have. But what are the symptoms of this code? Let’s elaborate and learn more about them in the following chapter.

P0171 Honda Accord Symptoms

We have covered the possible causes for the P0171 Honda Accord code and learned that there are more than a few of them. But what are the symptoms of this problem? There has to be some right? Let’s elaborate.

The first primary symptom of the P0171 code is probably the check engine light. Without the check engine light, you will never be able to tell that you have this code. This is obvious, but what are the less obvious symptoms? Let’s elaborate on them.

P0171 Honda Accord

The first very common symptom is the rough engine idle and engine misfires. Whenever there is a bad air-to-fuel mixture, the engine will simply feel ill and will run quite poorly. There will be misfires here and there and the engine work will resemble coughing than a properly running engine.

Then there are the other symptoms, the visual ones. If you decide to remove one of the spark plugs, you will probably notice how the electrode of the spark plug is white or even blistered. So, why is this the case?

Well, it’s because there is a lot of air and very little fuel. Spark plugs shouldn’t be like this and if you notice something like this, then you definitely have a lean condition in the engine.

How To Diagnose P0171 Honda Accord?

So, we learned more about the definition, causes, and symptoms of the P0171 Honda Accord. But how you can diagnose this problem the right way?

Well, for this purpose, you will need some tools and also some skills. In order to tackle this issue, you are going to need an OBD2 scanner to scan the car for codes, which you presumably already did. And also the second tool is a multimeter.

When it comes to broad generic codes like the P0171, there should probably be some other codes as well. Something connected with a certain sensor, ignition components, or fuel system-related stuff. And you should look at these codes and these will help you pinpoint the problem correctly.

Then for example, if there is a problem with the O2 sensor, for example, you can remove it and test it with the multimeter.

Each sensor has one ground wire, one signal wire, and one 5V supply wire. Figuring them out is relatively easy and not a big problem. In the video above, you can see how a guy tests the MAP sensor with a multimeter. For a specific MAF-related tutorial you can check other videos online. But the procedure is rather the same. If the sensor is good, under load it should produce a good signal. If it doesn’t produce a signal, the sensor is probably dead.

You should also check for vacuum leaks, these are the most common reasons why this problem appears. So, inspect the vacuum lines that go to bank 1, as well as the intake gaskets. You need to put your sleeves up because solving problems like these requires a lot of effort.

Cost To Fix P0171 Code

So, we learned what is the P0171 Honda Accord and learned more about the problem, the causes, and its symptoms. But what about the cost? How much money can you pay to sort this out?

Well, usually the cause of this problem is a sensor. Sensors are relatively inexpensive. In the worst case will cost you about $500 if you do this work at a shop. Or if you do this work at home, you will only pay for the sensor.

Conclusion To P0171 Honda Accord

In this article, we have covered quite a bit when it comes to the P0171 Honda Accord. We learned what this problem is and its definition. We also covered the causes as well as the symptoms that are most often associated with the problem.

Then we moved on to diagnosing and sorting this issue out. Remember that this is a rather broad problem and you need to look more at the specific codes for a certain sensor. So, if you get a code for the MAP, MAF, or O2 sensor, you know where to look. Thanks for reading and good luck with the troubleshooting.