Have you encountered the p0171 code on your Nissan dashboard, and now you’re dealing with a frustrating issue that can lead to severe potential damage if left unresolved? The Nissan p0171 code indicates that the air-fuel ratio in the engine is imbalanced, which means that it can impact engine performance and fuel efficiency and result in other potential damage.
In this guide, I will assist you in fixing the Nissan code p0171, identifying the common causes behind the fault, and taking easy steps to diagnose & resolve the issue. So, let’s make your vehicle safe from warning alerts.
What is the Nissan P0171 Code?
The Nissan code p0171 stands for “system tool lean (bank1)”, which means that more air is entered into the combustion chamber and less fuel is available, which forces the engine control module ( ECM) to trigger the warning p0171 on the dashboard. The engine needs the correct amount of fuel and air to perform its function, and when this mixture becomes too lean, it can reduce the engine’s performance.
Seven Potential Causes of the Nissan Code P0171
Several reasons can cause the indication of an error code, but here’s the breakdown of the seven most common causes that are often found behind the p0171 code flashing.
Vacuum Leaks
A vacuum leak is the most common culprit of error code, and its leakage occurs when any of the engine intake system components, such as vacuum hoses, manifold gaskets, and PCV valves, are cracked, damaged, or malfunctioned. Due to cracked vacuum leaks, more unmetered air enters the engine, forming a lean mixture containing too much air and less fuel.
Diagnosis
- First, stop the vehicle in a safe place and visually inspect the vacuum hoses to look for any cracks, damages, breaks, or disconnections.
- You can conduct a smoke test to detect leaks that aren’t easily visible. If you’re facing difficulty while performing the smoke test, then seeking professional help can help you do it.
Clogged fuel injectors
Fuel injectors spray the fuel into the engine’s internal combustion chamber to mix it with the air. When it becomes clogged or dirty, it will not be able to deliver the right amount of fuel needed for ignition. Due to the lack of fuel, the lean mixture is formed, which means blinking the p0171 code warning on the dashboard.
Diagnose
- Buy a high-quality fuel injector cleaner and put it into the gas tank to clean the fuel injector.
- To deeply clean and inspect the fuel injectors, remove them from the engine and then clean them if they are dirty. On the other hand, if the injectors are clogged and need replacement, you must replace them for optimal engine performance.
Faulty Oxygen Sensor (O2 Sensor)
The oxygen sensor’s main function is to monitor the air-fuel mixture in the exhaust gases and deliver its readings to the engine control module as electric voltage. When the O2 sensor becomes faulty, it will start transferring incorrect data to ECM, which results in inaccurate air-fuel mixture adjustment by the ECM, leading to a lean mixture and triggering the Nissan p0171 warning code.
Diagnose
- Check the voltage readings of the oxygen sensor with the help of an error code scanner.
- Remove the faulty O2 sensor and install a new one.
Malfunctioning Mass Air Flow (MAF) Sensor
The mass air flow sensor monitors and regulates the air entering the engine and sends its readings to the ECM. When the MAF sensor becomes faulty or fails to function, it will deliver incorrect signals to the ECM, forcing it to imbalance the air-fuel ratio. As a result, the lean mixture containing insufficient fuel and more air is produced, and the computer flashes the error on the dashboard to inform the owner about a critical issue.
Diagnosis
- Disconnect the MAF sensor.
- Carefully clean the MAF sensor with the help of a specialized cleaner used to clean the MAF sensor.
- Test the MAF sensor with a multimeter to ensure it’s functioning correctly.
Low Fuel Pressure
When the fuel pump or fuel pressure regulator becomes faulty, malfunctions, and fails to deliver sufficient fuel to the engine, it can impact the fuel delivery and result in a lean mixture. Due to low fuel pressure and a faulty fuel pump, less fuel is being transferred, which causes fuel depletion in the combustion chamber.
Diagnosis
- Test the pressure in the fuel system with the help of a fuel pressure gauge.
- Inspect the fuel pump and pressure regulator for damage or wear & tear.
ECM issues
In rare cases, an ECM can be a culprit that is not accurately calculating the fuel-air mixture. When any fault or error occurs in the ECM, it can’t function properly and can cause lean conditions.
Diagnosis
- Use a fault code scanner tool like OBD-II to detect ECM-related error codes.
- If any codes are found, fix each to normalize the ECM.
Dirty Air Filter
A dirty air filter is a very uncommon cause that can trigger the p0171 code Nissan, but understanding it is also important to fix the error code. A dirty air filter can’t monitor the accurate airflow and allows excessive air to enter the engine, which causes the Nissan p0171 error code.
Diagnosis
- Inspect the air filter by removing it and look for signs of wear and excessive dirt & debris.
- Replace the old, dirty, or faulty air filter and use a new one.
Brands Most Affected by the P0171 Code
You might wonder how many brands are affected by the DTC p0171 Nisan fault code. It’s a very commonly reported code among various famous vehicle brands filled with supreme features and functionalities. Below is a chart containing the most commonly affected car brands by the code p0171.
| Car Brand | Common Models Affected |
|---|---|
| Nissan | Altima, Sentra, Rogue, Maxima, Frontier |
| Kia | Optima, Sorento, Sportage, Forte, Soul |
| Hyundai | Elantra, Sonata, Santa Fe, Tucson, Veloster |
| Ford | F-150, Focus, Fusion, Escape, Explorer |
| BMW | 3 Series, 5 Series, X5, X3, 7 Series |
| Volkswagen | Jetta, Passat, Golf, Tiguan, Beetle |
| Dodge | Ram 1500, Charger, Challenger, Durango, Grand Caravan |
| Toyota | Camry, Corolla, RAV4, Highlander, Tacoma |
| Chevrolet | Silverado, Malibu, Equinox, Cruze, Impala |
Cost to fix the Nissan p0171 code
The actual cost of fixing the Nissan code p0171 can vary depending on the location, labor rates in your area, the make and model of the vehicle, and the quality of parts you’re using to install during replacements. However, there’s an estimated cost of each root cause you can expect to pay while visiting a mechanic shop.
| Cause | Estimated Repair Cost |
|---|---|
| Vacuum Leak Repair | $100 – $200 |
| MAF Sensor Replacement | $200 – $300 |
| MAF Sensor Cleaning | $10 – $20 (cleaning) |
| Fuel Injector Replacement | $200 – $400 |
| Fuel Injector Cleaning | $50 – $100 |
| Exhaust Leak Repair | $100 – $200 (minor repair) |
| Air Filter Replacement | $20 – $50 |
In A Nutshell
The Nissan p0171 code indicates a potential issue with the air-fuel mixture that can cause further damage if left unresolved. After encountering the p0171 code on your Nissan dashboard, you must first identify the issue’s main root, which needs timely repair or replacement. Understanding the most common causes of p0171 code Nissan and the way of diagnosing the faults can prevent you from costly repairs.
However, always inspect simple checks such as vacuum lines and air filters to easily fix the issue without consulting a mechanic. After that, if the problem remains, then check the complex inspections like fuel injectors, fuel pumps, and O2 sensors.
Frequently Asked Questions
What are the symptoms of a P0171 code in a Nissan?
Common symptoms of Nissan p0171 code include the check engine light, rough idling, poor acceleration, stalling, increased fuel consumption, reduced fuel efficiency, and engine misfires.
What does the Nissan code P0171 mean?
The P0171 code on the Nissan’s dashboard indicates that the engine’s air-fuel mixture is too lean on Bank 1, which can lead to severe significant issues such as poor engine performance and reduced fuel efficiency.
Can I drive my Nissan with a P0171 code?
No, driving for a prolonged period with a lean air-fuel mixture is not recommended because it can damage the engine’s health and impact overall vehicle performance.
How much does it cost to repair the P0171 code?
Fixing a P0171 error code varies depending on the root cause, ranging from $100 for a vacuum leak repair to $900 for replacing a fuel pump or pressure regulator.