Are you facing the P0171 code on your vehicle’s dashboard? Querious to know why it appears and how to fix it?
Well, some diagnostic trouble codes (DTCs) work in every vehicle to indicate the problems on the vehicle’s computer system. The P0171 is one of these (DTCs) that appears when your car’s engine control module (ECM) encounters a lean condition in the engine’s air-fuel mixture on the power bank 1.
Simply put, the air-fuel mixture is too lean in your vehicle, meaning there is extreme air and insufficient fuel to function properly. However, Toyota, Chevy, Ford, and Nissan are some vehicle brands that commonly experience that issue.
What Is The P0171 Code?
The numerical code P0171 is one of the most frequent diagnostic trouble codes (DTCs) related to fuel system problems. This error occurs when the oxygen sensor finds the lean fuel trim system (Bank 1). Therefore, a check engine light will come on the instrument cluster, and a diagnostic scanner will also help you to see the code.
P: Powertrain (System that supplies power to the wheels)
0: Generic code (applies on OBD-II-compliant vehicles)
1: Indicates a fuel and air metering problem
71: Special code that indicates a lean condition on Bank 1
Common Reasons For The P0171 Code
Various issues can be a reason for trouble code p0171; most are related to the fuel and intake systems of the vehicle’s engine. Moreover, the most common causes are as follows:
Vacuum Leaks
The vacuum plays a vital role in the vehicle system’s functions, like automatic transmission control and power steering. In condition to a vacuum leak, the extra air will enter the engine and lead to the lean mixture.
Faulty Mass Air Flow Sensor (MAF)
The MAF sensor operation measures the total amount of air that enters the engine. If the MAF is faulty or dirty, it can transfer the incorrect data to the ECM, causing an abnormal fuel mixture.
Dirty Or Clogged Fuel Injectors
Fuel injectors are crucial for delivering the fuel to the combustion chamber. Dirty or clogged fuel injectors may need to provide more fuel value, and that can lead to a lean condition.
Weak Fuel Pump (Can Lead P0171 Code)
Weak or clogged fuel pumps are also one of the common problems that can cause various vehicle issues. The main purpose of the fuel pump is to deliver the fuel to the engine. However, if a fuel pump is not functional precisely, it can affect the fuel economy and engine’s performance.
Exhaust Leaks
The exhaust system reduces the noise produced by the engine and channels the harmful gasses that are made in the combustion process, like carbon monoxide and carbon dioxide, away from the vehicles and into the atmosphere. The exhaust leaks can cause various issues, such as incorrect readings (leading to the engine system running lean) and fuel efficiency.
Faulty Oxygen Sensor
In modern vehicles, the oxygen sensor is an essential component that monitors the total amount of oxygen in the engine’s exhaust gasses. The engine control module (ECM) uses this information to adjust the fuel-to-air mixture. Therefore, a faulty oxygen sensor may send incorrect data to ECM, leading to an improper fuel mixture that can cause the code P0171 to occur.
Fuel Pressure Regulator Issues
The fuel pressure regulator is another crucial vehicle component that maintains the engine’s fuel pressure, ensuring the engine receives the correct and proper amount of fuel for high engine performance and efficiency. The malfunctioning fuel pressure regulator can cause insufficient fuel pressure, leading to a lean condition (Bank 1).
Symptoms Of The P0171 Code
Various Issues can trigger the P0171 problem code on the vehicle. The car tells you about those issues through its dashboard or other feature systems, and you also can identify them manually. However, here are some of the most common symptoms of the P0171 engine code:
Check engine light: The most frequent symptom is that a check engine light will illuminate the vehicle’s dash.
Poor fuel efficiency: The system’s too-lean condition can lead to the engine burning more fuel, decreasing fuel economy.
Rough Idling: The engine may be idling roughly due to the improper air-fuel mixture, which can be the reason for that code.
Engine stumbling: You may experience the engine stumbling or stalling while driving.
Engine Misfiring: A lean condition can be the reason for engine misfiring, leading to power loss and serious issues such as damaging the engine power.
Lack of power: Vehicles need more power and struggle to accelerate due to inadequate fuel.
How To Diagnose P0171 Engine Code?
To ensure the correct diagnosis for your vehicle, You or your mechanic should scan first for the code P0171. That’s why, before locating the issue’s cause, an OBD-II scan of your vehicle is vital.
Most drivers might think replacing some sensors will resolve the issue, but a proper and professional OBD-II scan will detect all the problems around Bank 1 of the engine. However, it is recommended that you (if you’ve diagnostics field experience) check for the P0171 engine code.
But if you’re just a car enthusiast and don’t have any special maintenance knowledge, you can get it from a mechanic; they will have advanced tools and expert-level knowledge to deep down analysis.
Moreover, a list of some areas to inspect is given below. After finding the P0171 Code, keep working on the issue until you figure out why the error is occurring:
- To locate leaks, use a vacuum gauge (only when the engine is off)
- A fuel pressure gauge is used to check the performance of the fuel sensor and mass airflow (MAF) sensor.
- Follow the manufacturer guidelines or owner manuals for testing oxygen sensors throughout the fuel system.
- Once you’ve applied all the steps, the issue likely lies in the control model.
How To Fix P0171 Code?
After applying some steps and procedures, you can resolve the Bank 1 System Too Lean error (P0171). So, here are some approaches that you can follow:
- Change the fuel filter and fuel pump.
- Replace the defective mass airflow sensor.
- Install a fresh fuel pressure regulator.
- Upgrade to a newer fuel injector.
- Seal the vacuum leak.
Repair Costs To Fix P0171 (Fuel Trim System Lean Bank 1)
To fix the fuel trim system lean problem, the repair costs can vary depending on the vehicle model, parts, and required maintenance. However, the estimated costs for that service are listed below:
| Issue | Repair Cost |
| Inspect for Vacuum Leaks | $20 – $150 |
| Clean or Replace MAF Sensor | $10 – $100 |
| Clean or Replace Fuel Injectors | $20 – $300 |
| Check the Fuel Pump and Fuel Filter | $50 – $500 |
| Repair Exhaust Leaks | $50 – $200 |
| Replace Oxygen Sensor | $100 – $300 |
| Test Fuel Pressure Regulator | $60 – $200 |
| Perform Comprehensive Diagnostic | $50 – $150 |
Required Tools For P0171 Code Fix
The mechanics use various advanced tools to diagnose and troubleshoot the issue; in my years of auto experience, I have also used different tools and gadgets to bring smiles to my customer’s faces.
So, a list of required tools to trouble code p0171 is given below that can help you if you’re going DIY service:
| Issue | Required Tools |
| Inspect for Vacuum Leaks | Vacuum gauge, Smoke machine, Basic hand tools (screwdrivers, wrenches) |
| Clean or Replace MAF Sensor | MAF sensor cleaner, Basic hand tools (screwdriver) |
| Clean or Replace Fuel Injectors | Fuel injector cleaner, Basic hand tools (wrenches, sockets) |
| Check Fuel Pump and Fuel Filter | Fuel pressure gauge, Basic hand tools (screwdrivers, wrenches) |
| Repair Exhaust Leaks | Exhaust leak detector, Basic hand tools (sockets, wrenches) |
| Replace Oxygen Sensor | Oxygen sensor socket, Ratchet, and extensions |
| Test Fuel Pressure Regulator | Fuel pressure gauge, Basic hand tools (wrenches, screwdrivers) |
| Perform Comprehensive Diagnostic | OBD-II scanner |
P0171 Code: Commonly Affected Car Brands
It is one of the generic OBD-II codes illuminated on any modern vehicle dashboard. However, due to their distinct design of manufacturing or component attributes, some vehicle brands are commonly affected by that issue. Here is the list of the most common ones:
- Toyota
- Chevrolet
- Ford
- Nissan
- Honda
- Volkswagen
- BMW
Preventive Measures and Maintenance Tips For The Code P0171
To prevent that problem code from recurring in your vehicle, regular inspection of fuel and intake systems and overall vehicle maintenance are the only things you can follow. Moreover, some maintenance tips and preventive measures are mentioned below:
Regularly Inspect Vacuum Hoses
The vacuum hoses play a crucial role in vehicles by transporting engines that create vacuum pressure. You can inspect them for signs of wear or damage. Brittle or cracked vacuum hoses can cause a lean condition, so ensure its replacement if you find any hoses brittle or cracked.
Keep the Mass Air Flow (MAF) Sensor Clean
The MAF is a significant element in managing a vehicle’s engine, counting the air (entering the engine). Clean MAF sensors ensure the precise readings of the air-fuel mixture, and dirty MAF sensors can be a reason for incorrect air-fuel readings.
Opt For Quality Fuel And Fuel Enhancements
High-quality fuel for your vehicle is crucial for long-lasting performance and a smooth driving experience, as it contains fewer impurities and reduces engine risks. Poor quality of the fuel can lead to injector clogging and lean conditions, too; however, premium quality fuel from reputable resources should always be used.
Regularly Monitor Fuel Pressure
Check the fuel pressure regularly to ensure the fuel pump and pressure regulator are working according to their specifications and manufacturers’ guidelines. Low fuel pressure and the issue with the pressure regulator can contribute to the system’s lean problem.
Conduct Routine Oxygen Sensor InspecAn oxygen
An oxygen sensor is one of the key features of the vehicle emission control system, which measures the amount of oxygen in exhaust gasses. So, also inspect the oxygen sensor while maintaining it (especially if your vehicle has a high mileage) because replacing the failed or damaged oxygen sensor can prevent your car from engine code P0171.
Examine The Air Intake System For Leaks
The air intake system is responsible for providing clean air to the engine, but an intake leak can also lead to excess air coming into the engine, which can cause a system’s lean condition.
However, examine the air intake system for leaks, wear, or damage. Early recognition and addressing of issues can prevent engine code P0171 from being illuminated.
Schedule Routine Diagnostic Checks
Regular diagnostic checks are essential to maintain your vehicle’s performance and prevent potential problems before they can occur. You can use an OBD-II scanner to run the diagnostic tests.
Change Fuel Filters At The Specified Intervals
Over time, the fuel filters can become clogged, restricting the fuel flow and leading to poor engine performance and reduced fuel economy. Therefore, the manufacturer’s recommendations and guidelines are the best things that you can follow for fuel filter replacement.
However, by following all these pre-venture measures and maintenance tips, you can reduce the chances of the P0171 error codes appearing on your instrument panel and enhance your vehicle’s optimal performance.
Comprehensive Guides! Code P0171 On Ford, Nissan, And Chevy
- P0171 Ford Code: System Too Lean (Bank 1) Causes And Fixes
- https://p0171code.com/nissan-p0171-code/
- Chevy Code P0171
In A Nutshell
The P0171 is a problematic code affecting many vehicles, including Toyota, Chevy, Ford, and Nissan. However, extra knowledge about its reasons, symptoms, and prevention measures can help you address and fix it effectively without compromising driving.
Regular inspections and scheduled maintenance ensure your vehicle’s health and help to maintain its longevity and performance. But if you’re a car enthusiast unsure about diagnosing or fixing vehicle issues, it’s always best to seek help from a professional mechanic.
Moreover, based on the expert’s guidelines, reviews, and my personal experience in the automotive industry, you should schedule maintenance regularly. This habit will save your vehicles from potential risks that can occur in the future.
FAQ’s – Frequently Asked Questions
What does the P0171 code mean?
P0171 is a diagnostic trouble code (DTC) that appears when your engine is running too lean; simply, it means too much air in the air-fuel mixture and insufficient fuel.
What are the symptoms of the P0171?
There are various symptoms of the code P0171, some of the most common being poor quality acceleration, rough idling, stalling, low fuel efficiency, and the appearance of the Check Engine Light.
What causes code p0171?
The most common causes for that code include faulty Mass Air Flow (MAF) sensors, vacuum leaks, clogged or damaged fuel injectors, exhaust leaks, or fuel pump or pressure regulator issues.
How do you fix code P0171?
Follow the comprehensive guide to trouble code p0171, also known as fuel trim system lean bank 1. But in a quick step, you can repair vacuum leaks, inspect fuel injectors, ensure cleaning or replacement of the MAF sensor, replace the oxygen sensor (if needed), or check the fuel pressure level and pressure regulator.
Will a p0171 code clear itself?
No, the code P0171 will not clear itself automatically. There are rare chances where a temporary issue might be the reason for the appearance, and the code disappears on its own. The check engine light may also temporarily turn off, but the foundational issue will still need to be resolved. To fully get rid of and solve the problem, you need to find its root cause and fix it.
Is it safe to drive with a P0171 code?
Driving with that code may not cause immediate or potential damage but can also reduce your vehicle’s performance and fuel efficiency. However, it is best to get it fixed when this code comes up because ignoring it for too long can lead to engine damage or other issues.
P0171 code comes and goes. What is the solution?
If you’re noticing the P0171 code comes and goes, it likely shows an irregular issue affecting the air-fuel mixture in the engine. However, you can start by checking vacuum leaks and loose or damaged hoses. Clean or change the MAF sensor, and check the fuel pressure and regulator. Inspect the fuel injectors and replace the failing oxygen sensors (if needed). Additionally, you can check for exhaust leaks and perform a full diagnostic scan. If the issue persists, then look for expert guidance.