P0171 Chevy Cruze code – how to deal with it?

If you notice p0171 code Chevy Cruze code on the OBDII scanner, do not ignore it in any case. This error is related to the ratio of air and fuel that enters the engine. This applies to Chevy Cruze engines of any displacement 1.4, 1.6, 1.8.

The ratio of air and fuel is controlled by several parts of the car together. Sensors, injectors, and onboard computer (ECM) thus show whether the system is in lean condition or saturated. To put it simply, too much fuel makes the system saturated, and too much air makes it lean.

How serious is p0171 code Chevy Cruze?

The OBDII code Chevy Cruze P0171 is a generic code for “System Too Lean (Bank 1)”. In some cases, the scan may also show the general wording “Fuel Trim System Lean Bank 1”.

“Fuel Trim System Lean Bank 1” is related to the feedback compensation value. It consists of both short-term and long-term fuel trims. The short-term fuel trim is gas compensation that is used to constantly maintain the air-fuel ratio at stoichiometric levels.

The main message of this error is to worry about the ratio of air/fuel in the engine and diagnose the problem.

You can also get code P0171 when the Intake Manifold is corroded in some areas. If you have a leaky intake manifold gasket, so during the replacement in many cases you should also replace the fuel pressure regulator.

What causes p0171 code?

Below we have compiled the most common problems that can cause this code to appear.

1. Vacuum leak from the engine.

Vacuum leaks are the most common cause of the Chevy Cruze p0171 code. The air/fuel ratio changes due to leakage, resulting in a check engine light for the P0171 code. A vacuum leak is fairly easy to diagnose, sometimes just strain your ears and hear it.

If the leak can’t be perceived by the ear, we recommend using a vacuum test machine (smoke machine). It organizes the flow of smoke into the engine, and vacuum leakage can be visualized.

2. PCV valve is broken.

The leaking PCV valve is a problem, which reason is a vacuum leak. You can also identify the problem by ear since a vacuum leak is characterized by a hissing sound.

How do you fix a Chevy P0171 in this case?

The PCV valve is located inside the valve cover on Chevy Cruze vehicles, so you will have to buy a whole valve cover to replace it.

3. Defective Mass Air Flow Sensor

The Mass Airflow Sensor (MAF sensor) can be the source of the problem if it is dirty or defective. More frequent are situations with pollution. This is easily fixed with a MAF cleaner. If the part is broken, it is worth buying a new Mass Air Flow Sensor and replacing it.

After checking your MAF sensor, check for carbon buildup around the bore of the throttle body and under the valve. Sometimes, it can also cause problems.

4. Faulty oxygen sensors

The onboard computer receives part of the information for analysis using 2 oxygen sensors. They are divided into upstream and downstream.

A faulty sensor will provide false data for analysis, and the service engine code p0171 is then displayed on an OBDII scanner connected to a working car. Most often, problems arise with the upstream sensor.

5. Bad fuel injectors.

Fuel injectors are needed to distribute gas to the cylinders. If the injectors are faulty, then the fuel supply is not working properly and the air/fuel ratio changes – there is not enough fuel.

This can occur due to contamination or failure of one or more injectors, and the gas supply is reduced by up to 40% of the amount that should be atomized, which causes a lean condition.

Replace bad fuel injectors or clean them for proper gas delivery.

6. Terribly dirty air filter

Logically, a dirty air filter will not let enough air into the engine, which will change the air/fuel ratio. Remember that a dirty air filter is an unacceptable item, as it can lead to incorrect operation of other elements of the car, for example, it will contaminate the MAF sensor.

7. Bad fuel pressure regulator or dirty fuel filter

A dirty fuel filter blocks the gas supply to the engine, and if a faulty fuel pump does not supply gas – the car will not be able to start. Or the fuel pump will work, but badly, and the pressure will drop very much.

8. Broken EGR system

The EGR system is designed to process exhaust gases into more environmentally friendly substances. A broken EGR system can reduce the vacuum level in your Chevy Cruze and generate codes P0171 and P0174.

How do I fix my P0171 Chevy Cruze?

You need to urgently diagnose the problem with the following symptoms:

  • Fuel consumption may be suspicious, depending on how much the air/fuel ratio has changed.
  • Idle Issues – the vehicle idles unevenly when the air/fuel ratio changes because the onboard computer will try to compensate by changing the fuel supply. The engine may also splash.
  • Misfire or Rough Vehicle Ride – if the air/fuel ratio is approaching critical, you will have these symptoms along with the display of codes P0171 and P0174, and P0300.

Once your vehicle has these symptoms and is diagnosed, replace or clean the defective part as soon as possible, as trying to compensate for the problem on your own wears out and breaks down even more.

Read also How To Reset Transmission Control Module Chevy in our new article.


In this article, we have tried to collect the main problems that cause the code P0171 on the Chevy Cruze, and their solutions.

We hope that you will be able to diagnose the problem yourself and in time. Check this article about P0171 Chevy Cruze Diagnosis and Explanation to learn how to do it right.

Remember that ignoring such errors is equal to reducing the performance and durability of your car.

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