Audi VW P0171 Fault Code

Audi VW P0171 Fault Code

Did you encounter a P0171 Fault Code when reading the codes on your Volkswagen? Learn what the code means and know the possible solutions for the fault code on your Volkswagen.

This code affects many models and engines, including VW Polo 1.2, Passat 1.8T 2.0T, Jetta (Bora) 1.8T 2T 2.5, Golf 1.6, CC, Rabbit, GTI, Fehler, Beetle and Audi A3, A4, A6, TT.

What does the Audi VW P0171 code mean?

Combustion engines are designed to run most efficiently when they have the correct ratio of air to fuel mixture. That ideal ratio is 14.7 parts air to 1 part fuel. The P0171 error code tells you that a lean condition exists, which means the ratio of air to fuel is off, and there’s too much air in the system.

In this article, we’ll break down the symptoms, causes, and possible solutions for this error code so you can get your Volkswagen properly functioning again.


The P0171 error code can come with a lot of symptoms. First, the check engine light in your car will turn on. Any time this happens, it’s always a good idea to read the codes using an OBD2 scanner or, even better, to use a VW Audi Scanner.

Another symptom may be your car has performance problems, such as misfiring or a lack of power while accelerating. Your car also might have trouble idling at a stoplight or stop sign. Your vehicle may also experience strange noises while driving or in traffic.

Another symptom may be that you have a hard time starting your car. Or it’s possible that the engine may die while you’re driving it.

Common Causes

As mentioned before, the VW P0171 error code is triggered in your car when a lean condition exists, meaning there is too much air and not enough fuel. A few different reasons can cause this. It’s important to figure out the actual cause before jumping to a solution because the different causes have different solutions.

And if you don’t fix the real problem, you’ll just keep getting this error. So make sure you check all possible causes to see what’s going on before trying to fix anything.

Mass Air Flow Sensor

vw  audi p0171 code

One of the reasons you may be getting this error is a dirty or broken mass airflow sensor (MAF Sensor), which detects how much air is flowing into your engine.

If this isn’t working properly, more air may get into your engine than detected, causing the lean ratio that triggers a P0171 error. It may also be that the control module software needs to be updated. This software helps regulate the air and fuel ratio in your engine.

Oxygen Sensor

audi vw check engine light on due to bad oxygen sensor

It is possible that the Volkswagen Code P0171 is caused by a defective Oxygen sensor sending values that are out of range. A bad O2 sensor is less likely the cause. Check that there are no vacuum leaks before replacing this sensor.

Vacuum Leaks

Vacuum leaks are also common causes of this kind of error being triggered in your car. If there are vacuum leaks, the air gets into your engine that can’t be auto-detected and corrected by the machine sensors, so it causes the lean condition.

A weak fuel pump or plugged fuel filter may also cause the fuel not to get into the engine in the right ratio. Dirty or plugged fuel injectors might cause this as well.

Frequently Asked Questions

How severe is a VW P0171 error code?

Moderate; you can still drive for a little while after you get this error code. But driving with this error code for too long can cause serious problems in your engine.

Is this error commonly misdiagnosed?

Yes, many people will misdiagnose this error code as a problem with the oxygen sensors when the issue could be something else like vacuum leaks.

Why does running a car too lean matter?

Cars that run too lean cause a lot of pollution. It can also cause your car to misfire or overheat, which is never fun and can harm your car.

What is the most common cause of the P0171 error code?

Intake leaks are the most common cause, but it is not the only cause, so don™t jump to conclusions when you get this error. Be sure to check all common causes mentioned earlier to make sure you correctly diagnose the problem.


Knowing how to diagnose and properly treat the cause of this error code is essential to maintaining your car in perfect working order.

  • Troubleshooting the VW P0171 error code on your car can be tricky. But now you know that this code indicates a lean condition in your combustion engine. This is because the air-to-fuel ratio is off what it should normally be.
  • Check all of your vacuum lines and hoses for leaks. If you find any, then replace them. You can also repair other intake leaks.
  • Replacing the PCV, EVAP, and EGR valves can sometimes fix this problem. If the issue is because of a problem with the mass airflow sensor, try removing it and cleaning it or replacing it altogether.
  • If the issue persists after you’ve replaced any leaky vacuums and cleaned the mass airflow sensor, running a fuel pressure test is a good idea. This will tell you if you need to replace the fuel pump, fuel filter, or fuel pressure regulator.

These are the most common solutions for the P0171 error code. A lean condition means that there is too much air in the ratio. Knowing this and being aware of the common causes of this error code will help you find the best solution for fixing it.

Although this error code isn’t a severe threat to your car or your safety, you don’t want to be driving around with this issue for too long, as it could cause issues and create more pollution.

After reading this article, you now know what this error code means, how to diagnose the cause, and how to solve the issue correctly.

We hope you find the Audi VW P0171 Fault Code guide helpful. Check these troubleshooting and repair guides for more help on your Volkswagen.


  • Rushit Hila • ASE Certified

    Rushit Hila, an ASE-certified engineer (G1 Automotive Maintenance and Repair), brings over two decades of hands-on experience in the automotive world to his writing. With a strong educational background, including a Master of Science in Engineering and a Bachelor of Science in Engineering, he has honed his skills and expertise through years of practical work. As a respected authority in the field, Mr. Hila is dedicated to offering insightful and valuable content that resonates with both vehicle owners and mechanics.

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