Home TroubleshootingOBD Codes P0171 Chevy Cruze – Fuel System Too Lean (Bank 1) Meaning

P0171 Chevy Cruze – Fuel System Too Lean (Bank 1) Meaning

by Kelvin Yates

Your engine needs the proper mixture of fuel and air to operate effectively. Your combustion engine won’t operate as effectively or efficiently as it should if it is too much or insufficient, your car will record a P0171 Chevy Cruze if the combustion chambers are being flooded with air.

This rise in oxygen levels can be brought on by a number of problems, from a broken sensor to a problem with your fuel pump or vacuum system. Before your car sustains significant damage, it’s critical to identify the core problem fast. Only the best air-to-fuel ratio can guarantee good performance and fuel efficiency.

Continue reading to discover more regarding identifying the source of the P0171 Chevy Cruze, comprehending how it could impact your car, and resolving the issue.

Chevy Cruze

P0171 Chevy Cruze

Having debuted on the market in 2008 and having been produced worldwide since 2009, the Cruze is a small automobile. In 2010, this car took the position of the Chevy Cobalt. It is a four-door sedan that was also offered in 2011 and 2012 as a five-door hatchback and a station wagon.

Sadly, Chevy stopped making this vehicle in Mexico and the United States in 2019. However, it is still produced and offered elsewhere in the world. If you’re thinking of getting a used example and wonder whether or not are Chevy Cruze good cars, be wary of the common Chevrolet Cruze problems.

That includes getting into detail with the 2012 Chevy Cruze problems, and the 2014 Chevy Cruze problems, as well as the 2016 Chevy Cruze problems.


Your car’s engine will wear out with time, and the sensors may occasionally fail to measure accurately. When this occurs, the fuel injectors will get adjustments from the car’s computer to better balance the fuel and air combination. The system too lean P0171 error code will then appear for this problem.

A P0174 code can appear along with the P0171 Chevy Cruze when it does. Because of this code, Bank 2 is also recognized as lean. 14.7 parts air to 1 part gasoline is the ideal ratio. Your car’s improved performance, lesser pollutants during combustion, and what is considered good gas mileage all result from the combination of these two banks.

Given the complexity of most engine vacuum systems, practically anything in the system can experience a leak. Therefore, it is strongly advised to have a vacuum system diagram for the affected application on hand to determine the cause of the P0171 Chevy Cruze.

However, unless the vacuum leak is visibly caused by a busted, split, or detached vacuum hose, other potential leaks could be caused by deteriorated or damaged input manifold gaskets, splits and/or tears in the inlet ducting, or other issues.

For more context, we’ve looked at this diagnostics code in general before. In addition, similar OBD error codes to that. Previously, we’ve looked into P0171, P0171 Chevy, and P0171 Ford, as well as P0172, P0172 Chevy, and P0174 (or the P0174 Chevy code).

P0171 Chevy Cruze Symptoms

You might not notice any difference in how your car runs when the  Chevy Cruze check engine light turns on in some cases. There will be additional symptoms if the light is present together with a P0171 Chevy (after checking for issue codes).

Your engine cannot run properly if there is too much air within. You might hear the engine coughing or notice a noisy idle when your engine is running, but you aren’t driving. When you try to speed or travel uphill while you are driving, your car could seem to be lacking in power. Your engine misfiring may even be audible or felt.

A defective sensor may be the cause of your P0171 Chevy code if you don’t notice any changes in how it drives. They do break down. Even so, you still need to make sure the components surrounding the sensor are in good working order. You don’t want to replace a pricey component pointlessly.

P0171 Chevy Cruze Causes

The P0171 Chevy might have numerous causes. As was already reported, the engine is running lean in all of them. This might be caused by either not enough fuel or too much air in the combustion chamber.

The following are some of the contributing factors of PO171:

  • Bad mass airflow sensor
  • Vacuum leak
  • Bad fuel pump/filter
  • Bad oxygen sensor

The four factors listed above or anything roughly similar to them is nearly invariably the cause. Below, we’ll go over each of the potential causes indicated above.

P0171 Chevy Cruze, Causes #1: Faulty Mass Airflow Sensor

The mass airflow sensor’s function is self-explanatory: it measures the amount of air entering the engine. This sensor may occasionally become dirty or stop functioning altogether, necessitating replacement; however, a simple cleaning will occasionally restore the MAF’s functionality.

It is feasible to read the value of the MAF sensor output if you have a scan tool on hand. An aberrant reading would indicate that the MAF sensor is the source of the issue. The cost to replace a mass air flow sensor is between $200 and $300 to replace a mass airflow sensor.

But you should clean it first because there is a good chance it will be enough to solve the issue. If your MAF sensor is faulty, you might also find accompanying error codes. That includes P0101, and P0101 Chevy Silverado or the P0101 code Nissan, as well as P0102, among others.

P0171 Chevy Cruze, Causes #2: Leaky Vacuum

A minor crack in the intake manifold is frequently referred to as a vacuum leak. This overwhelms all essential sensors and draws air into the engine. Too much air will be present in the cylinder because more air is drawn into the combustion chamber without the car ECU being informed in advance.

It can take a long time and be difficult to locate a vacuum leak. The best method for finding a leak is to pinpoint it using a propane torch. Depending on the model of your car, the cost to repair a vacuum leak on the intake manifold might range from a few hundred dollars to several thousand dollars.

P0171 Chevy Cruze, Causes #3: O2 Sensor Issue

The amount of O2 in the exhaust is determined by O2 sensors, and the ECU uses this information to modify the air/fuel mixture. The engine will run too richly or leanly as a result of a malfunctioning O2 sensor. Feel free to head over to our guide on your car running rich or the P0175 error code for more insight on the former.

Which sends the ECU the incorrect parameters. It is crucial to remember that improper combustion, brought on by other factors, will result in a high O2 concentration in the exhaust, which will cause the engine to run lean.

This indicates that something other than the O2 sensor could be to blame for the aberrant air-to-fuel ratio. Therefore, it’s crucial to examine each potential issue and determine which is more likely. If it turns out that the O2 sensor is the issue, the replacement cost of an O2 sensor will run you about $100.

So, you’ll have to be wary of the bad O2 sensor symptoms. Besides that, if your O2 sensor is going awry, you might also notice diagnostics error codes such as:

When an engine is running lean, the issue may not always be a lack of air but rather a lack of fuel for a number of different reasons. A faulty fuel pump, a clogged fuel filter, and blocked fuel injectors are a few examples of fuel-related issues that result in a lean air/fuel mixture.

P0171 Chevy Cruze

P0171 Chevy Cruze, Causes #4: Poor Fuel Pump Or Filter

A clogged fuel filter will partially block the fuel that the fuel pump is sending. Increasing the workload on the fuel pump and increasing the risk of it breaking down. Driving an automobile with little fuel in the tank is another way a fuel pump can fail.

So, make sure you’re diligent about the symptoms of a bad fuel pump, or a bad fuel pump relay. You might also want to check out our guide on the fuel pump replacement cost to find out what it entails. And while you’re there, make sure you look up the symptoms of a bad fuel filter (and the signs of a bad fuel filter) and the replacement cost of a fuel filter.

This is a problem since the fuel cools the pump, and more fuel in the tank makes it easier for the pump to transfer fuel. Additionally, clogged and dirty fuel injectors prevent the proper quantity of fuel from reaching the combustion chamber, causing the engine to run low.

It can be expensive to replace fuel injectors, especially if you drive a high-end model. In some circumstances, expert fuel injector cleaning will work. If it turns out that you need to replace the fuel injectors. They typically cost around $200 each, and each cylinder has one.

The fuel injector replacement cost can be high, but doing so is vital to prevent further harm to the fuel system. Therefore, be wary of any symptoms of a bad fuel injector. Otherwise, if it’s not too badly wrong, a simple and the best fuel injector cleaner is enough to fix it.

Code P0171 Chevy Cruze: Is It Serious

Take the reading carefully whenever your  Chevy Cruze check engine light is on. This regulation does not apply to the P0171 code. You shouldn’t drive your car very far, if at all when the engine stores this code.

When your engine is running lean, it lacks the fuel it needs to function properly. You run the danger of the car losing its ability to accelerate quickly enough to keep up with oncoming traffic or to climb a steep incline. The vehicle can possibly overheat and break beyond repair.

P0171 codes are more likely to appear in turbocharged vehicles whose boost has been increased. Generally speaking, more air results in more power, but more fuel must be added to maintain the air-to-fuel ratio. Your car is not using its fuel effectively if code P0171 is present, at the very least. Every time you drive, you’ll waste gas and money.

Common Errors Made When Fixing P0171 Chevy Cruze

The most frequent error in diagnosing this code is failing to take into account any potential extra codes. Which causes confusion, incorrect diagnoses, lost time, and the needless replacement of parts and components.

  • Low fuel pressure circumstances will invariably be signaled by codes that relate specifically to the fuel system and the fuel pressure. Even though low fuel pressure can produce lean-running conditions over prolonged durations. A typical reason for moderately low fuel pressure that may or may not result in a fault code is dirty and/or blocked fuel filters.
  • This code can also be caused by faulty oxygen and air/fuel ratio sensors. However, these malfunctioning sensors will almost always be detected by codes that directly relate to these sensors.
  • The fuel trim system lean can also be caused by or contribute to malfunctioning or blocked fuel injectors. However, keep in mind that separate codes will almost always indicate these problems.
  • This code can also be set or contributed to by defective MAF sensors. Although again, malfunctioning MAF sensors will most likely be indicated by specific codes. MAF sensors with flaws “under-, or over-report” the amount of air passing through them.

However, in some circumstances, such as on applications that utilize large amounts of oil (BMW, Mercedes, Audi, VW, Honda). A straightforward cleaning of the MAF sensor element will frequently cure this code even if no other codes linked to the MAF sensor are present.

The initial step in identifying/fixing code P0171 on the aforementioned applications should be cleaning the MAF element using a recognized cleaning solution.

P0171 Chevy Cruze Diagnosis

If no other fault codes are present, a mechanic can identify the fuel trim system lean by checking the engine for suction leaks with a vacuum gauge and a vacuum gauge.

  • A hissing sound caused by a vacuum leak is typically only noticeable when the engine is turned off.
  • The MAF and fuel pressure sensors are inspected using a fuel pressure gauge (mass air flow).
  • For the engine to maintain the proper air/fuel ratio, the vacuum and fuel pressure must be within the manufacturer’s specifications. The source of this error number will, therefore, typically be found using these two checks.
  • After the mechanic has performed these two inspections and the cause is still unclear, the issue is most likely with a sensor.
  • The mass airflow and oxygen sensors would next be tested by the mechanic using the manufacturer’s method.
  • If all of these tests are finished without finding any issues. The powertrain control module is most likely to be the problem.

And if you’re curious, we’ve also written up extensive guides on what a fuel system cleaning process entails. Additionally, we’ve even discussed the cost of wanting to clean out your fuel system.

How To Troubleshoot P0171 Chevy Cruze

A portable vacuum pump with a graduated gauge must diagnose this error code.

Step 1:

Write down all fault codes and freeze frame data that are present. If an intermittent defect is later identified, this information may be helpful.

Step 2:

If additional codes are present, resolve all such codes precisely in the order in which they were saved in accordance with the directions in the handbook for the concerned application before operating the vehicle and rescanning the system to check if code P0171 reappears.

Step 3:

It would be safe to presume that the issue is unmetered air entering the engine if no other codes are present. Checking for leaks in the input tract is the first step in the diagnostic process. Look for splits, tears, or perforations in soft, flexible ducting. If necessary, fix the damage or replace the affected inlet tract portions.

Pay close attention to the locations where various sensors attach to or plug into the ducting. Verify that every seal is in excellent shape and replace any that are not. Check the tightness of all the clamps and/or clips that connect the various components of the input tract. As well as the condition and seal of the box that houses the air filter.

As necessary, make repairs. After repairs are finished, erase all codes and drive the car normally before rescanning the system to check for any resurfacing codes.

Step 4:

If the inlet tract is in excellent condition, but the code or symptoms continue. Check the whole engine vacuum system for frayed, detached, split, perforated, or hardened vacuum hoses or lines.

Note that in some circumstances, it might be necessary to remove shields and other obstructions to access certain vacuum system components or components that are vacuum powered.

To remove covers, shields, and other items blocking access to all vacuum system components, follow the instructions in the manual. Before running the car normally and running the system through again, check if any codes reappear. Replace any plainly broken vacuum lines or hoses.

Step 5:

If the error code still appears, find any vacuum check valves, actuators, and other vacuum-dependent or -controlled components using the vacuum diagram. Verify that the air only flows through each individual check valve in the direction that is always indicated on the valve with an arrow or some other device.

Any vacuum check valve that permits airflow in both directions should be replaced. Test each vacuum actuator to ensure it can withstand the vacuum created by the manual vacuum pump. Any actuator where the vacuum is steadily vanishing should be replaced.

After repairs are finished, erase all codes and drive the car normally before rescanning the system to check for any resurfacing codes.

Step 6:

Suspect a leaky intake manifold gasket if the code continues despite the engine vacuum system being intact and clear of leaks. However, non-professional mechanics should be aware that removing an inlet manifold is frequently challenging and requires specialized equipment and abilities that most non-professionals do not have.

Therefore, the better choice is to send the car to the dealer or another capable repair facility for professional assistance if there is any uncertainty regarding your ability to remove and reinstall a manifold and its gasket effectively.

System Too Lean Bank 1 Repair Cost

Have you ever received the engine-related error code “fuel trim system lean bank 1”? If so, you might have a problem that needs to be fixed right away in order to prevent more engine damage.

This problem may be a sign of one or more issues with the air-fuel mixture in your car’s engine. Most of the time, an imbalance between the two is caused by a leak or another problem.

Repairing a vacuum leak, replacing fuel injectors, and replacing the fuel filter are a few common fixes made to address a fuel trim system lean bank 1 issue. Based on individual fixes, the typical cost to fix a “system too lean P0171” issue ranges from $80-$950.

Depending on the repairs or replacements your vehicle needs. When it comes to the air-fuel combination, this particular problem is caused by the engine having either too little fuel or too much air.

A weak fuel pump, a clogged fuel filter, a broken fuel pressure regulator, malfunctioning injectors, defective sensors (mass airflow), a failing powertrain control module, or repairing a vacuum leak by changing the PCV valve hose are some of the remedies we’ll examine that can solve this issue.

P0171 Chevy Cruze

FAQs On P0171 Chevy Cruze

How To Fix P0171 Code

System Too Lean (Bank 1) is the diagnosis trouble code (DTC) for P0171. Numerous things can cause this; thus, a technician must identify the precise cause in your case in order to clear the code.

What Is Code P0171

When your car’s powertrain control module (PCM) notices that the air-to-fuel ratio is too lean, a P0171 code is set. This indicates that the PCM is signaling that the engine is burning too much fuel while receiving too much air into the combustion chamber.

What Does Code P0171 Mean

Either too much oxygen or insufficient fuel in the exhaust are the causes of a Code P0171 or System too lean p0171. This is a low fuel trim code or a ‘lean’ state.

What Does System Too Lean Bank 1 Mean

This error code indicates that the system is underperforming on the first engine bank and cannot provide fuel to the engine. This code may also indicate that the engine’s fuel trim system, lean bank 1, has a vacuum leak. Which could lower pressure and result in an unbalanced fuel-to-air ratio. When the engine receives either too little fuel or too much air, the condition is known as being too lean.

What Causes P0171 And P0174 Codes

A vacuum leak is the most common cause of an illuminated Chevy Cruze check engine light and P0171 and P0174 stored codes. These codes are set when the car’s computer notices excessive oxygen in the exhaust. Oxygen levels in the exhaust that are too high create lean codes.

What Does Running Lean Mean

When an engine operates lean, there is too much air in the air-to-fuel ratio. As we previously discussed, most engines require a particular ratio of air and fuel to carry out a flawless combustion cycle.

Will A Bad Fuel Pump Throw A Code

When you attempt to start your car in the morning and the fuel pump one day decides to stop working, it probably won’t set a code. However, if the problem is with the wiring, the PCM might be able to identify it on its own and set a circuit high or circuit low Diagnostic Trouble Code.

Will A Bad O2 Sensor Cause Car To Shut Off

Yes, a bad O2 sensor can, sadly, cause your automobile to stall. The amount of oxygen in your engine is monitored by the O2 sensor in your car. A very exact ratio of oxygen to gas is required for combustion to occur properly in an engine. The engine will operate less effectively or perhaps not at all when this ratio is off.

How Much Is Fuel Filter Replacement

A fuel filter replacement service should cost between $50 and $175 for the majority of autos, according to certain websites that list auto service prices. For between $10 and $70 if you are skilled around the engine. You can get the part and install it yourself.

Will A P0171 Code Clear Itself

The likelihood is that it won’t. Get it checked out as soon as you can if you notice this code.

How To Fix Bad Gas In Car

On the other side, fixing faulty gas is significantly easier. You will need to empty the gas out of your tank and pump new gas in if the gas is truly rotten and not just old or waterlogged. Don’t play around with this because poor gas can harm you even if it just seldom occurs.

Will A Vacuum Leak Throw A Code

Yes, The combination of air and fuel varies due to a vacuum leak.

Is Bank 1 Upstream Or Downstream

Bank 1 is located on both sides of the engine. So, neither bank 1 is upstream nor downstream. Based on their positions, the upstream and downstream sensors, the housing for both sensors 1 and 2, are chosen. Therefore, bank 1 has a downstream sensor as well as an upstream sensor.

What Part Do I Need For A Code P0172

P0172 denotes the detection of excessive gasoline in the exhaust gasses leaving the combustion chamber. The mass air flow sensor (MAF), oxygen sensors, and manifold absolute pressure (MAP) are just a few of the devices the ECU uses to track the engine’s air-fuel ratio.

What Are The Symptoms Of A Bad Powertrain Control Module

Poor engine performance and a dashboard check engine light are the two most typical signs of a faulty PCM. The transmission may also be having troubles, such as shifting difficulty. Increased emissions and poor fuel economy are also very typical.

P0171 Chevy Cruze: Final Verdict

The P0171 Chevy Cruze indicates that the combustion chamber is either too airy or too fuel-starved, causing the engine to run lean. There are numerous possible reasons why the engine is running lean, including excess air entering the combustion chamber due to a vacuum leak or inadequate fuel delivery due to a fuel system malfunction.

Whatever the situation, it’s critical to deal with the issue and find a solution as quickly as possible to prevent more harm to the engine and all components. Misfires, subpar engine performance, stalls, and choppy idles are symptoms that could also be present in addition to a P0171 code.

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